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Elements  of  Drawing 


BY 

GEORGE  F.  BLESSING,  M.E.,  PH.D. 

Professor  of  Mechanical  Engineering  and  in  charge  of  Engineering,  Swarthmore  College 
Formerly  Assistant  Professor  of  Machine  Design,  Cornell  University 

AND 

LEWIS  A.  DARLING,  E.  IN  M.E. 

Engineering  Department  Remy  Electric  Co.,  Formerly  Assistant  Professor  of 
Machine  Design,  Cornell  University 


FIRST  EDITION 

SECOND   THOUSAND 


NEW  YORK 

JOHN    WILEY   &   SONS 

LONDON:  CHAPMAN  &  HALL,  LIMITED 
1913 


BY  THE  SAME  AUTHORS 


ELEMENTS   OF  DESCRIPTIVE 
GEOMETRY 

8vo,  xvii  +219  pages,  168  figures.  Cloth, 
$1.50  net. 

CONTENTS. —  Preface.  Introduction.  Definitions, 
Notation  and  First  Principles,  Problems  on  the 
Point.  Point  and  Line  Problems.  Line  and  Plane 
Problems.  Solids.  Tangent  Planes  and  Double- 
Curved  Surfaces  of  Revolution.  Sections.  Inter- 
sections and  Developments. 


COPYRIGHT,  1912, 

BY 
GEORGE   F.  BLESSING  AND   LEWIS   A.   DARLING 


Stanbopc  jprcss 

F.    H.  GILSON   COMPANY 
BOSTON,  U.S.A. 


PREFACE 

IT  is  the  purpose  of  this  book  to  present  a  course  of  instruc- 
tion in  Elementary  Drawing  for  beginners  who  intend  to  pursue 
a  course  in  engineering  or  who  desire  to  prepare  themselves  to 
do  commercial  drafting.  The  work  herein  outlined,  as  well  as 
that  contained  in  the  companion  volume,  "Elements  of  De- 
scriptive Geometry"  by  the  same  authors,  is  based  on  the 
drawing-room  courses  required  of  all  first-year  students  in 
Mechanical  and  Electrical  Engineering  in  Sibley  College,  Cornell 
University,  as  a  preparation  for  the  more  advanced  work  of 
design  in  the  second  and  third  years  of  the  course,  which  is  also 
required  of  all  students  in  the  college. 

The  task  of  writing  the  book  and  its  companion  volume  was 
undertaken  by  the  authors,,  at  the  writer's  request,  while  they 
were  members  of  the  staff  of  instruction  of  the  Department  of 
Machine  Design  and  Construction  of  Sibley  College.  The  object 
in  view  was  twofold,  namely,  to  obtain  a  book  exactly  suited  to 
the  needs  of  the  Department,  which  we  had  heretofore  been 
unable  to  do;  and  also  to  put  into  permanent  shape  the  methods 
and  principles  used  in  this* work,  thus  forming  one  of  a  correlated 
series  of  texts  which  eventually,  it  is  expected,  will  fully  cover 
the  entire  work  of  the  department.  The  authors  brought  to 
the  task  a  full  knowledge  of  the  more  advanced  work  of  the 
Department,  having  had  experience  in  teaching  these  advanced 
subjects  in  design  which,  with  their  experience  elsewhere  both  in 
practical  and  teaching  positions,  was  of  great  aid  in  improving 
and  refining  this  more  elementary  work. 

There  is  nothing  experimental  in  the  principles  or  methods 
outlined  in  the  book,  as  most  of  them  have  been  in  constant  use 
in  Sibley  College  for  years  and  have  been  productive  of  most 
excellent  results,  not  only  in  teaching  the  art  of  elementary 
drawing  but  as  a  preparation  for  the  more  advanced  work  in 
design. 


295883 


vi  PREFACE 

Particular  attention  is  given  in  the  drawing-room  work  in 
Sibley  College  to  the  art  of  lettering  and  the  methods  presented 
in  the  chapter  on  lettering  have  been  remarkably  successful. 
Only  two  alphabets  have  been  presented,  it  being  considered 
best  to  confine  the  student's  efforts  to  a  thorough  study  and 
practice  of  those  two  which  are  of  almost  universal  use  rather 
than  to  make  a  superficial  study  of  more  elaborate  alphabets 
which  find  very  limited,  or  no  use.  The  system  of  spacing  was 
very  largely  developed  by  Prof.  John  T.  Williams,  who  has 
taught  it  for  a  number  of  years  with  marked  success.  The  authors 
have  refined  the  system  and  also  developed  and  presented  a 
spacing  chart,  as  it  is  believed  that  some  instructors  may  prefer 
its  use  to  that  of  rules. 

In  regard  to  the  material  on  "drawing-room  system,"  no 
claim  is  made  by  the  authors  that  it  is  the  best  in  the  sense  that 
there  is  a  best  system,  but  it  is  their  belief,  which  is  based  on 
considerable  experience,  that  if  this  system  is  well  understood 
by  the  student  he  will  have  no  trouble  in  understanding  any 
other  he  may  be  called  upon  to  work  with. 

Chapter  V  has  been  presented  because  of  the  growing  popu- 
larity of  isometric  drawing  in  practically  all  branches  of  tech- 
nical work. 

It  will  be  noted  that  though  the  book  is  based  on  the  practice 
of  Sibley  College  it  is  written  in  a  flexible  manner  so  as  to  be 
adaptable  to  almost  any  logical  sequence  of  presentation,  the 
general  text  matter  applying  equally  to  the  drawing-board 
course  presented  or  to  a  beginners'  course  arranged  by  in- 
structors in  the  subject.  The  following  suggestions  by  the 
authors  as  to  the  use  of  this  book  will  make  this  clearer. 

The  text  matter  is  intended  to  give  in  a  practical  and  concise 
form  such  information  as  the  beginner  should  have  in  order  to 
intelligently  pursue  the  drawing-board  work. 

It  is  not  supposed  that  lessons  be  assigned  for  recitation  after 
the  manner  usually  followed  in  teaching  textbooks,  that  is,  by 
beginning  with  Chapter  I  and  assigning  consecutive  para- 
graphs to  the  end.  The  paragraphs  should  be  assigned  at  the 
time  the  information  can  be  applied  directly  to  the  drawing 
being  executed.  To  facilitate  this  method  each  drawing  plate 


PREFACE  Vii 

has  certain  paragraphs  assigned  and  at  the  completion  of  the 
plate  there  should  be  an  examination,  oral  or  written,  covering 
these  paragraphs.  The  proper  method  of  covering  the  text 
previous  to  examinations  will  depend  upon  the  methods  of  the 
institution  using  the  book.  It  is  most  desirable  to  have  regular 
recitation  periods,  and  the  authors  believe  one  hour  per  week 
upon  recitation  should  cover  the  work  satisfactorily.  Where 
this  is  impracticable  the  instructor  should  question  the  student 
as  he  proceeds  with  his  work  in  the  drawing-room.  Especial 
attention  should  be  directed  to  points  where  the  student's  work 
shows  a  lack  of  knowledge  and  he  should  be  required  to  refer 
at  this  time  to  the  parts  of  the  text  covering  the  points  in  ques- 
tion. 

Where  the  book  is  used  in  this  manner,  that  is,  simply  as  a 
book  of  reference,  a  preliminary  examination  should  be  held 
after  the  completion  of  each  plate.  The  instructor  should  con- 
stantly keep  in  mind  the  object  of  this  book,  which  is  to  teach 
the  student: 

ist,  how  to  select,  care  for,  and  use  drawing  instruments. 
2nd,  how  to  make  and  read  technical  drawings. 
3rd,  how  to  think  over  the  drawing  board. 
4th,  to  lead  him  to  consider  the  relation  drawing  bears  to 
design,  shop  processes,  and  shop  organization. 

The  third  and  fourth  items  are  not  usually  given  the  attention 
their  importance  demands,  and  it  is  not  unusual  to  see  a  college 
graduate  make  a  beautiful  drawing  whjch  is  full  of  errors,  due 
to  the  fact  that  all  thought  has  been  given  to  the  drawing  paper 
and  none  to  the  object  it  represents  or  to  the  shop  methods 
necessary  to  produce  this  object.  To  aid  in  overcoming  this 
difficulty  the  authors  have  avoided  the  use  of  models  of  the 
geometric  or  kindergarten  type  or  of  machine  parts  selected 
at  random. 

The  models  selected  are  parts  of  a  wood-turning  speed  lathe, 
and  are  selected  because  the  students  will  most  likely  be  more 
familiar  with  this  machine  than  any  other.  Also  in  most 
places  where  this  course  is  taught  the  student  will  be  working  on 
his  wood-turning  exercises  in  the  shop,  on  this  machine,  at  about 


viii  PREFACE 

the  same  time  he  is  doing  his  drawing.  For  this  reason  he  is 
most  apt  to  study  the  principles  of  design  involved,  the  relation  of 
parts,  etc.,  and  thus  do  his  work  in  a  much  more  intelligent 
manner  than  if  he  held  no  further  interest  in  the  model  than 
that  of  making  a  dimensional  picture  of  it. 

DEXTER  S.  KJMBALL, 
Professor  of  Machine  Design  and  Construction, 

Cornell  University. 
June  8,  1912. 

AUTHORS'   NOTE 

The  authors  are  deeply  indebted  to  Prof.  J.  T.  Williams  of 
Sibley  College,  Cornell  University,  without  whose  assistance 
and  cooperation  this  book  in  its  present  form  would  not  have 
been  possible. 

Grateful  acknowledgment  is  also  made  of  assistance  by  Prof. 
D.  S.  Kimball  in  developing  the  book  and  outlining  its  scope, 
and  to  Prof.  G.  W.  Lewis,  Messrs.  A.  Kessler  and  L.  J.  Brad- 
ford for  assistance  in  preparing  material  and  reading  proof. 


CONTENTS. 


PAGE 

FRONTISPIECE i 

Perspective  View  of  Wood-turning  Speed  Lathe.  —  Partial  Longi- 
tudinal Section  through  Headstock.  —  Partial  Longitudinal  Section 
through  Tailstock. 

PREFACE v 

General  Purpose  of  the  Book.  —  Basis  on  which  the  Book  is  Planned.  — 
Special  Attention  Given  to  Lettering.  —  Growing  Popularity  of  Iso- 
metric Drawing.  —  Flexibility  of  the  Book.  —  The  General  Text  to  be 
Referred  to  as  Needed  and  Consecutive  Text  Lessons  not  to  be  Given. 
—  Points  to  be  Kept  in  Mind  by  the  Instructor.  —  Models  Selected  for 
the  Courses  in  Drawing  are  Parts  of  a  Wood-turning  Speed  Lathe.  — 
Author's  Acknowledgment. 

CHAPTER  I. 

SELECTION,  CARE  AND  USE  OF  DRAWING  INSTRUMENTS  AND  MATERIALS. 
SEC. 

1.  Introductory i 

Quality    of    Instruments.  —  Care    of    Instruments.  —  Description    of 
Instruments  and  Supplies. 

2.  List  of  Instruments  and  Supplies  Necessary  for  Complete  Courses. .        2 

3.  Drawing  Paper 4 

Selection.  —  Quality.  —  Paper  for  Inked  Drawings.  —  Paper  for  Pencil 
Drawings.  —  Working  Side.  —  Detail  Manila  Paper.  —  Whatman  Paper. 

4.  Ruled  Paper 5 

Purpose.  —  Cross-section  Ruling.  —  Isometric  Ruling.  —  Cleaning  Ruled 
Paper. 

5.  Tracing  Paper 6 

Description.  —  Blue  Prints  from. 

6.  Tracing  Cloth 6 

Description.  —  The  Glazed  Side.  —  The  Dull  Side.  —  Cutting  Tracing 
Cloth  to  Size.  —  Quality  to  Use. 

7.  Blue-print  Paper 6 

Description.  —  Formula  for  Making  Blue-print  Paper.  —  Storage. 

8.  Drawing  Boards 7 

Material  and  Design.  —  Testing. 

9.  Thumb  Tacks 

Best  Design.  —  Use  of. 

ix 


X  CONTENTS 

SEC.  PAGE 

10.  T-Squares 8 

Purpose.  —  Design  and  Materials.  —  To  Test.  —  Care  of.  —  Use  of. 

11.  Triangles 10 

Design   and   Materials.  —  Desirable   Size.  —  Testing   the   Angles   and 
Edges.  —  Use  of. 

12.  Irregular  Curves 13 

Design  and  Materials.  —  Use  of. 

13.  Pencil  Pointer 14 

Design  and  Use  of. 

14.  Lead  Pencils 14 

Essential  Qualities.  —  Commercial  Rating.  —  Design  of.  —  Care  of.  — 

To  Sharpen.  —  The  Cone  Point.  —  The  Chisel  Edge.  —  To  sharpen  Lead 
for  Bow  Pencil  or  Compass. 

15.  Erasers  and  Erasures f 16 

Purpose  and  Quality.  —  Method  of  Making  Erasures. 

16.  Erasing  Shield 17 

Use  and  ^Design  of. 

17.  Soapstone 18 

Description  and  Use  of. 

18.  Drawing  Ink 18 

Requirements  of   a  Good   Drawing  Ink.  —  Colored   Drawing  Inks.  — 

»  Care  of. 

19.  Ordinary  Pens 18 

Description  of  Common  Styles.  —  Ball-pointed  Pen.  —  Crow-quill  Pen. 

—  Selecting  a  Pen.  —  "Breaking  in"  and  Use  of  Pen. 

20.  Pen  Holders 20 

Design  of. 

21.  Ruling  Pens 20 

Design  and  Materials.  —  To  Adjust.  —  To  Fill.  —  Proper  Use  of.  — 
Care  of.  —  To  Clean  Pen  Blades.  —  To  Sharpen.  —  To  Test. 

22.  Compasses 23 

Purpose.  —  Names  of  Parts.  —  Materials  of.  —  Design  of.  —  The  Socket- 
joint  and  Head-joint  Design.  —  The  Needle  Point.  —  The  Extension 
Bar.  —  To  Prepare  and  Use  the  Compass. 

23.  Dividers 26 

Purpose.  —  Design  and  Materials.  —  Use  of. 

24.  Bow  Dividers 27 

Purpose  and  Advantage. 

25.  Bow  Pencils , 27 

Purpose  and  Advantage- —  Ordinary  Design  of.  —  Materials  of. —  Special 
Design  of.  —  To  Prepare  the  Bow  Pencil.  —  To  Test. 

26.  Bow  Pens 28 

Purpose.  —  Requirements.  —  Care  and  Use  of. 

27.  Scales 29 

Purpose.  —  Engineer's     Scale.  —  Architect's     Scale.  —  Materials     and 
Design.  —  Scale  of  Triangular  Cross  Section.  —  Proper  Use.  —  To  Test. 

28.  Protractors 31 

Purpose.  —  Materials  and  Design,  —  Use  of. 


CONTENTS  XI 

SEC.  PAGE 

29.  Machinist's  Calipers,  Dividers,  and  Steel  Rule 32 

Use  of.  —  Materials  and  Design.  —  Outside  Calipers.  —  Inside  Calipers. 
—  Proper  Use  of  Calipers.  —  Design  and  Use  of  Dividers.  —  Microme- 
ters and  Extremely  Accurate  Measurements. 

30.  Blotter,  Penwiper,  and  Instrument  Rag 33 

Use  of  Blotter.  —  Use  of  Linen  Pen  Rag.  —  Use  of  Instrument  Rag. 


CHAPTER  II. 
LETTERS,  NUMERALS,  AND  LETTERING. 

31.  Introductory 34 

Importance  of  Good  Lettering.  —  Simple  Style  of  Lettering.  —  Gothic  • 
Alphabet.  —  Ability  to  Letter. 

32.  The  Study  of  Lettering 34 

Not  a  Purely  Mechanical  Process.  —  Outline  and  Characteristics  of 
Letters.  —  Grouping  of  Letters.  —  Sense  of  Proportion.  —  Practice  and 
Patience.  —  Critical  Study  of  Lettering. 

33.  Slope  of  Letters 36 

Advantages  of  the  Inclined  Alphabet.  —  Slope  Used  in  this  Work,  and 
how  Obtained. 

34.  General  Description  of  Model  Letters 37 

The  Stem,  Definition  of.  —  Top,  Bottom,  and  Side  Guide  Lines.  —  Center 
Lines  in  lettering.  —  Dimensions  on  Model  Letters.  —  Slope  of  Model 
Letters.  —  Direction  Arrows  with  Numbers.  —  System  of  Strokes. 

35.  Spacing . 39 

Importance  of  Correct  Spacing.  —  How  to  Judge  Spacing.  —  Distance 
between    Letters.  —  Element    of  Adjacency,    Defined.  —  Spacing    for 
Various  Line  Combinations  in  Capital  Letters.  —  Spacing  of  Numerals. — 
Spacing  of  Capital  Letters  in  Combination  with  Small  Letters  and  of 
Small  Letters.  —  Spacing  between  Words.  —  Spacing  between  Sentences. 

—  Spacing  Allowed  for  Punctuation  Marks. 

36.  Systematic  Method  of  Lettering 44 

37.  The  Size  and  the  Lettering  of  Letter  Sheets 44 

SET  OF  FREE-HAND  LETTERING  EXERCISES 

38.  Outline  and  Characteristics  of  Capital  (or  Upper-case)  Letters  . 

Composed  of  Straight  Lines  Only 44 

Detailed  Description  of   each  of   the  Following  Straight-line  Capital 
Letters:  /,  L,  F,  E,  II,  T,  N,  M,  Y,  V,  X,  A,  K,  Z  and  W. 

39.  Sheet  A 4» 

Exercise  in  Making  Large-size,  Straight-line  Capital  Letters  Free-hand. 
(See  Fig.  39,  page  49.) 

40.  The  Sloping  Ellipse 5° 

Construction  of.  —  Medium  Slope.  —  Extreme  Slope. 

41.  Outline  and  Characteristics  of   Capital  (or  Upper-case)  Letters. 

Composed  Wholly  or  Partly  of  Curved  Lines 51 

Detailed  Description  of   Each  of  the   following  Curved-line  Capital 
Letters:  0,  Q,  C,  G,  D,  U,  J,  P,R,B,  S,  and  the  Abbreviation  &. 


xii  CONTENTS 

SEC.  PAGE 

42.  Sheet  B 54 

Exercise  in  Making  Large-size,  Curved-line  Capital  Letters  Free-hand. 
(See  Fig.  41,  page  55.) 

43.  Sheet  C 56 

Exercise  in  Making  Capital  Alphabet  Free-hand  to  a  Reduced  Size.     (See 

Fig.  42,  page  57.) 

44.  Outline  and  Characteristics  of  Numerals 58 

Detailed  Description  of  each  of  the  Numerals:  4,  7,  o,  g,  6, 5,  8,  j,  and  2. 

45.  Sheet  D 60 

Exercise  in  Making  Numerals  of  Both  Large  and  Reduced  Size  Free- 
hand.    (See  Fig.  43,  page  6 1.) 

46.  Sheet  E 60 

Free-hand  Exercise  in  Making  Slant,  Capital,  Gothic  Letters  of  a  Size 
Suitable  for  Notes  on  Drawings.     (See  Fig.  44,  page  62.) 

47.  The    Small    (or    Lower-case)    Letters    of    the    Inclined    Gothic 

Alphabet.  . 60 

Detailed  Description  of  Each  of  the  Lower-case  Letters  Grouped  as 
Follows:  o.  —  a,  d,  g,  q.  —  b,  p. —  c,  e.  —  n,  r,  h,  m.  —  u,  y.  —  /,  i,  k, 
t,f,j-  —  s.—v,  w.  —  x.  —  z. 

48.  Sheet  F 67 

Free-hand  Exercise  in  Making  the  Small  (or  Lower-case)  Letters  to  a 
Large  and  Reduced  Scale.     (See  Fig.  45,  page  68.) 

49.  Designing  Headings  and  Titles 69 

50.  Sheet  G 69 

Free-hand  Lettering  Exercise  in  Laying  Out  a  Practical   Title   Form 

and  Bill  of  Material.     (See  Fig.  47,  page  70.) 

51.  Examination  on  Chapter  II 69 


CHAPTER  III. 
MECHANICAL  DRAWING  AND  DRAFTING  ROOM  PRACTICE. 

52.  Introductory 71 

The  Purpose  and  Field  of  Drawing.  —  A  Perspective  Drawing.  —  A 
Mechanical  Drawing.  —  Symbols  and  Notes  on  Drawings. 

53.  Projection  and  Projected  Views 73. 

Orthographic  Projection.  —  Vertical  Plane  of  Projection.  —  Horizontal 
Plane  of  Projection.  —  Third  Angle  Projection.  —  Various  Methods  of 

"  Folding  "  Planes  of  Projection.  —  Plan  View.  —  Side  Elevation.  — 
Front  Elevation. 

54.  Conventional  Lines 76 

Contrast  between  Lines.  —  "Weight"  of  a  Line,  Denned. —  Construction 

and  Weight  of  the  Visible  Line,  the  Invisible  Line,  the  Section  Line,  the 
Dimension  Line,  Arrow  Heads,  the  Reference  Line,  and  the  Center 
Line.  —  Symbol  for  Center  line.  —  A  "  Finished  "  Line.  —  A  Clear-cut 
Line.  —  A  Line  Free  from  Waves.  —  A  Line  of  Unvarying  Width.  — 
A  Line  Colored  to  the  Same  Degree  throughout. 

55.  Sectioning  and  Sectional  Views 79 

Purpose  of  a  "  Section."  —  Longitudinal  Section. —  Transverse  Section. — 
Simple   Section.  —  Compound   Section.  —  Conventional   Sectioning.  — 
Sectioning  Adjoining  Pieces.  —  A  Number  to  Represent  a  Material.  — 


CONTENTS  xiii 

SEC.  PAGE 

How  to  Draw  and  Space  Section  Lines.  —  Section  Liner.  —  To  Section 
a  Large  Area.  —  Location  of  the  Section.  —  Certain  Details  not  Sec- 
tioned. —  A  Quarter  Section  View.  —  A  "Turned-up"  Section. 

56.  Number  and  Arrangement  of  Views 83 

Determining  on  the  Views,  their  Number  and  Arrangement. — Views 
Arranged  According  to  Third  Angle  Projection.  —  Position  in  which  to 
Represent  a  Part.  —  Blocking  Out  the  Sheet. 

57.  Detail  Drawings 85 

Purpose  of  a  Detail  Drawing.  —  The  Number  of  Parts  Detailed  on  a 
Single  Sheet.  —  Operation  Sheets.  —  Grouping  Parts  on  a  Sheet.  —  Work- 
ing Up  the  Views. 

58.  Assembly  Drawings 86 

Purpose  of  Assembly  Drawings.  —  Dimensions  on  Assembly  Drawings. 

59.  Conventional  Methods 87 

Various  Uses  of.  —  Lack  of  Uniformity  in  Common  Conventions  (see 
Fig.  65,  page  88).  —  Conventional  Method  of  Showing  Each  of  the  Fol-    y 
lowing:    Solid  Shaft,  Bearing,  Timber  Section,  Hollow  Shaft,  Holes 
Equally  Spaced  Around  a  Circle,  Broken  Lines  to  Represent  a  Moving 
Arm  in  Extreme  Positions,  Broken  Lines  to  Represent  a  Part  in  Several 
Positions,  Broken  Lines  to  Represent  a  Part  not  Completely  Drawn, 
Visible  V  Threads,  Invisible  V  Threads,  Square  Thread,  National  Acme 
Thread,  Drilled  Holes,  Tapped  Holes,  Reference  Numbers,  and  Cross- 
section  of  Steel  Shapes. 

60.  Drawing  to  Scale 9° 

Explanation  of.  —  Method  of  Making  a  Scale.  —  "Scales  "  in  Common 
Use.  —  To  "Read"  a  Scale.  —  Shrink  Rule  for  Pattern  Makers. 

61.  Choice  of  a  Scale  in  Drawing 93 

Best  "Scale"  to  Use.  —  To  Determine  the  Largest  Scale  Permissible.  — 

To  Find  the  Scale  for  Each  of  Several  Parts  Represented  on  the  Same 
Sheet. 

62.  Dimensioning  Working  Drawings 94 

Importance  of  Dimensions. — How  to  Select  the  Dimensions.  —  When 
Dimensioning  is  Satisfactory.  —  Results  of  Inaccurate  Dimensioning.  — 

To  Check  Dimensions.  —  Dimensions  not  to  Scale.  —  Arrowheads,  Loca- 
tion of.  —  Dimension  Numbers,  the  Selection  and  Location  of.  —  Abbre- 
viation for  "Feet."  —  Symbol  for  Inches.  —  Refinement  in  Dimensions. 
—  Dimensioning  Rough  Castings.  —  Limits  in  Dimensioning.  —  Overall 
and  Sub-divided  Dimensions.  —  Repetition  of  a  Dimension.  —  Distribu- 
tion of  Dimensions. — Dimensioning  Similar  Parts.  —  "Leader,"  Defini- 
tion of.  —  Dimensions  which  Fall  on  a  Sectioned  Area.  —  Dimensioning  a 
Circle,  a  Cored  Hole,  Fillets,  a  Radius,  a  Threaded  Piece,  a  Tapped  Hole, 
Angles  and  Tapers. 

63.  Notes  on  a  Drawing •  •       °7 

When  Necessary.  —  How  to  Compose  and  Lay  Out.  —  Style  of  Lettering 

to  Use  in  this  Work. 

64.  Indicating  the  Finish  of  Surfaces 9& 

When  a  Surface  is  "Rough."  —  When  a  Surface  is  "Finished."  -  Some 

of  the  Kinds  of  Shop  Finishes.  —  To  Indicate  the  Finish  Desired. 


xiv  CONTENTS 

SEC.  PAGE 

65.  Use  of  Record  Forms  and  Titles 98 

A  Complete  Record  of  Each  Drawing  is  Essential.  —  Information  which 

is  Necessary  and  which  Should  be  Recorded.  —  Changes  on  Drawings, 
Record  of. 

66.  The  Title-form  on  a  Drawing 100 

Location.  —  No  One  Standard  Form.  —  Title  Form  Used  in  this  Work. 

—  Style,  Size  and  Arrangement  of  Lettering  in  Title  Form. 

67.  Bill  of  Material 101 

Where  Used  and  Purpose  of.  —  Form  Used  in  this  Work.  —  Location  of. 

—  Style  and  Size  of  Lettering  to  Use  in.  —  Complete  Explanation  of  the 
Bill  of  Material  Form  to  be  Used.  —  How  to  Call  for  Standard  Parts.  — 
Materials,  Abbreviations  of,  in  Bill  of  Material. 

68.  Numbering  and  Indicating  the  Size  of  Drawings 103 

Purpose  of.  —  Sizes  Most  Generally  Used.  —  Size  of  Paper  for  Mechan- 
ical Drawings  in  this  Work.  —  Numbering  of  Drawings  in  this  Work. 

69.  Part  Numbers  on  a  Drawing 104 

Purpose  and  Location  of.  —  Layout  of  Part  Numbers  Used  in  this 
Work. 

70.  Recording  Patterns  on  a  Drawing 104 

Purpose  and  Method  of  Numbering  Patterns.  —  Method  of  Selecting 

and  Recording  Pattern  Numbers  to  be  Followed  in  this  Work. 

71.  Time  Keeping  in  Drawing 105 

Method  and  Purpose  of,  in  Practice.  —  System  of,  in  this  Work. 

72.  Border  Lines 106 

Location  and  Purpose  of.  —  To  Lay  Out  Border  Lines  in  this  Work. 

73.  To  Fasten  the  Paper  or  Tracing  Cloth  to  the  Board 107 

Method  of  Procedure.  —  Location  of  Paper  and  Tracing  Cloth  on  the 
Board  in  this  Work. 

74.  To  Make  a  Pencil  Drawing 108 

General   Instructions.  —  Systematic   Procedure   and   Specific   Instruc- 
tions in  this  Work. 

75.  Inking  Drawings no 

To  Prepare  the  Pencil  Drawing  for  Inking.  —  Inspecting  the  Ruling 

Pen  and  "Charging"  it  with  Ink.  — To  Keep  the  Ruling  Pen  Working 
Satisfactorily.  —  General  Instructions  for.  —  Faulty  and  Ragged  Lines. 

—  Drawing  Ink  not  to  be  Blotted.  —  Ink-bottle  Holders.  —  Specific 
Instructions  for  Inking  Drawings  in  this  Work. 

76.  Checking  Drawings 113 

Importance  of  Efficient  Checking.  —  General  Discussion  on.  —  Specific 
Instructions  for. 

77.  Tracing 114 

A  Tracing,  Defined.  — Use  of  a  Tracing.  —  How  to  Make  a  Tracing.  — 
Moisture  Spoils  Tracing  Cloth.  —  To  Clean  Tracing  Cloth.  —  Erasures 

on  a  Tracing. 

78.  Blueprints 1 16 

How  Made.  —  Changes  on. 


CONTENTS  xv 


SET  OF  MECHANICAL  DRAWING  EXERCISES 

SEC.  PAGE 

79.  Drawing  C-ioi n6 

Detail  Drawings  of  Lathe  Spindle,  Key,  Fiber  and  Steel  Washer,  and 

of  Special  Nut  (see   Fig.  82,  page   1 1 8).  —  General   and  Specific  In- 
structions for  Making. 

80.  Tracing  Drawing  C-ioi 121 

General  and  Specific  Instructions  Given. 

81.  Blueprint  of  Tracing  C-ioi 121 

Purpose  of  Making.  —  Specific  Instructions  Given. 

82.  Drawing  C-I02 122 

Detail  Drawing  of  Lathe  Leg.     (See  Fig.  85,  page  123.) 

83.  Drawing  C-i<>3. 124 

Detail  Drawing  of  Lathe  Bed  and  Bracket.     (See  Fig.  88,  page  125.) 

84.  Drawing  C-IO4 126 

Drawings  of  Bolts,  Nuts  and  Screws,  the  Proportions  of  which  are  De- 
termined by  the  Student  from  Empirical  Formulas  Given  in  the  Text. 
(See  Fig.  89,  page  128.) 

85.  Tracing  Drawing  C-I02 129 

86.  Tracing  Drawing  C-ioa 129 

87.  Drawing  C-ios 129 

Detail  Mechanical  Drawings  made  from  Sketches  of  the  following  Lathe 
Parts:    Tail  Stock  Center,  Shell,  Tail  Stock  Spindle  and  Tail  Stock 
Spindle  Clamp. 

88.  Drawing  C-io6 130 

Assembly  Drawing  of  Lathe  Tail  Stock  Complete,  Built  Up  from  Draw- 
ings or  Sketches  of  Each  of  the  Parts  Composing  it. 

89.  Tracing  Drawing  C-io6 130 

90.  Examination  on  Chapter  III r 130 


CHAPTER  IV. 
FREE-HAND  WORKING  SKETCHES. 

91.  Introductory 131 

Value  of  Free-hand  Sketches.  —  Some  Uses  of  Free-hand  Sketches. 

92.  Free-hand  Copies  of  Working  Drawings 131 

Purpose  of  Making. 

93.  Free-hand  Sketches  from  Objects 132 

Working  Sketch,  Defined. —  Importance  of  Making  Sketches  Correct.  — 
Discrimination  in   Selecting  and  Placing  Dimensions  on  Sketches.  — 
Proportioning  Sketches  by  the  Eye  and  without  Direct  Measurements. 

—  To  Make  an  "Eye  Estimate"  of  a  Distance. 

94.  Making  Sketches  from  Memory 134 

Good  Method  of. 

95.  The  Free-hand  Pencil  Line i34 

The  First  Essential.  —  Specific  Instructions  for  Making.  —  Drawing  a 
Horizontal  Free-hand  Line.  —  Drawing  a  Vertical  Free-hand  Line.  — 
Manipulating  the  Pencil.  —  To  Draw  a  Curved  Free-hand  Line. 


XVl  CONTENTS 

SEC.  PAGE 

96.  Free-hand  Inked  Line 136 

Penciled  Work  to  First  be  Correct.  —  Specific  Instructions  for  Drawing 

a  Free-hand  Inked  Line.  —  Effects  of  too  Much  and  too  Little  Ink  on 
the  Pen.  —  Care  of  Pen. 

97.  Building  up  a  Sketch 137 

Determining  on   the  Views.  —  To  Begin  a  View.  —  Building  up   and 
Completing  a  Sketch,  General  Method  of. 

98.  Title  Form  on  Small  Sheets 138 

Title  Form  on  Sketch  Sheets  in  this  Work.  —  Style  of  Lettering  in. 

99.  Size  and  Numbering  of  Sketch  Sheets 139 

Standard  for  this  Work. 


SET   OF  FREE-HAND   DRAWING  EXERCISES 

100.  Sheet  No.  i 139 

Free-hand  Sketches  of  Lathe  Shim,  Small  Stud,  and  Clamp  Stud  (see 

Fig.  97,  page  140).  —  General  and  Specific  Instructions. 

101.  Sheet  No.  2 141 

Sketch  of  Main  Casting  of  Lathe  Headstock  (see  Fig.  99,  page  143). 

—  Specific  Instructions. 

102.  Sheet  No.  3 142 

Sketches  of  Lathe  Face  Plate,  Tail  Stock  Center,  and  Special  Nut. 
(See  Fig.  104,  page  145.) 

103.  Sheet  No.  4 144 

Sketches  of  Lathe  Tail  Stock  Spindle  and  Shell.     (See  Fig.  105,  page  146.) 

104.  Sheet  No.  5 147 

Sketches  of  Lathe  Clamp  Bolt,  Hand  Wheel  and  End  Cap.     (See  Fig. 

109,  page  148.) 

105.  Sheet  No.  6 147 

Sketch  of  Lathe  Clamp  Copied  from  Model  Sketch,  the  Dimensions  for 
which  are  Obtained  by  Direct  Measurement  of  the  Clamp  and  which  are 
Recorded  on  the  Exercise  Sketch.     (See  Fig.  in,  page  149.) 

106.  Sheet  No.  7 150 

Sketch  of  Lathe  Tool  Rest  Support  Slide  and  of  Lathe  Clamp  for  Tail 
Stock   Spindle.    These  sketches  are   made  directly  from  the  objects 
themselves. 

107.  Sheet  No.  8 ^o 

Sketch  of  Lathe  Tail  Stock  Screw  and  of  Tail  Stock  Nut.     (See  Fig.  1 16, 
page  151.) 

108.  Sheet  No.  9 *S2 

Sketch  of  Main  Casting  of  Lathe  Tail  Stock.     (See  Fig.  119,  page  153.) 

109.  Sheet  No.  10 *52 

Sketches  Made  Directly  from  Lathe  Bearing  Cap  and  Stationary  Flange. 

no.   Sheet  No.  u XS2 

Sketch  of  Lathe  Cone  Pulley  Made  on  Plain  Paper  (not  Cross-section 

Paper)  and  Directly  from  the  Part  Itself. 
in.   Sheet  No.  12 J5* 

Copying  a  Sketch  of  the  Pattern  and  Core  Box  of  Lathe  Cone  Pulley. 

(See  Fig.  122,  page  155.) 


CONTENTS  XVli 

SEC-  PAGE 

112.  Inking  Sheet  No.  i I54 

This  exercise  gives  practice  in  making  free-hand  inked  straight  lines. 

113.  Inking  Sheet  No.  2 z^ 

This  exercise  gives  practice  in  making  free-hand  inked  curved  lines. 

114.  Inking  Sheet  No.  n z^4 

This  exercise  gives  practice  in  inking  on  ordinary  unruled  paper. 

1 15.  Examination  on  Chapter  IV z 54 

CHAPTER  V. 

ISOMETRIC  DRAWING  AND  SKETCHING. 

116.  Introductory z^6 

General  Discussion  of  the  Subject  of  Isometric  Drawing.  —  Some  Uses 

of  Isometrics.  —  Advantages  and  Disadvantages  of  Isometric  Drawings. 

117.  Principles I57 

Statement  of  Important  Principles  on  which  Isometric  Drawing  is  Based. 

118.  Isometric  Drawing  of  a  Cube 157 

Method  of  Constructing. 

1 19.  Definitions 158 

Definition  of  Isometric  Axes,  Isometric  Origin,  an  Isometric  Line,  and 

a  Non-isometric  Line.  —  How  Measurements  must  be  Made  in  Iso- 
metric Drawing. 

120.  Isometric  Drawing  of  a  Circle 159 

Method  of  Constructing.  —  Definition  of  "Construction  Lines"  and 

' '  Isometric  Posi  tion . " 

121.  Approximate  Method  of  Making  an  Isometric  Drawing  of  a  Circle.     160 

122.  Isometric  Drawing  of  a  Plane  Figure  Composed  of  Straight  and 

Curved  Lines 160 

General  Method  of  Constructing. 

123.  Isometric  Drawing  of  a  Cube  Cut  by  a  Plane 161 

General  Method  of  Constructing. 

124.  Isometric  Drawing  of  Wall 162 

With  Axes  in  Ordinary  Position.  —  With  Axes  Reversed. 

125.  Isometric  of  a  Cylinder 163 

Method  of  Constructing. 

126.  Isometric  of  Screw  Thread 163 

Method  of  Showing  "Conventional"  Isometric  Thread. 

127.  Hollow  Cylinder  with  a  Quarter  Section  Removed 164 

Isometric  Drawing  of  Lathe  Spindle  Taken  as  an  Example. 

128.  Offset  Construction  in  Isometric  Drawing 164 

129.  Isometric  Drawing  of  a  Sphere 165 

General    Method    of    Constructing.  —  Isometric   Drawing   of   a   Half 
Sphere;   of  One-eighth  of  a  Sphere. 

130.  Isometric  Drawing  of  Lathe  Cap 166 

General  Method  of  Constructing. 

131.  Size  and  Numbering  of  Sketch  Sheets 166 

Isometric-ruled  Paper. 


Xviii  CONTENTS 


SET   OF  FREE-HAND   ISOMETRIC   EXERCISES 

SEC.  PAGE 

132.  Sheet  1 167 

Isometric  Sketch  of  Tool  Rest  Support  Slide  for  Lathe  (see  Fig.  138, 
page  1 68).  —  General  and  Specific  Instructions. 

133.  Sheet  II 169 

Isometric  Sketches  of  Lathe  Key,  Shim,  Stud,  Washer  and  Special  Nut. 

(See  Fig.  144,  page  170.) 

134.  Sheet  III 171 

Isometric  Drawing  of  Lathe  Collar  and  Bearing,  the  drawing  and  all 
dimensions  made  by  reference  to  the  objects  themselves. 

135.  Sheet  IV 171 

Isometric  Drawing  of  Lathe  Spindle,  the  drawing  to  be  inked  and  made 
from  observation  of  the  object  itself. 

136.  Sheet  V 172 

Isometric  Drawing  of  Lathe  Cap. 

137.  Sheet  VI 172 

Isometric  Drawings  of  Lathe  Shelf-Bracket.     (See  Fig.  150,  page  173.) 

138.  Examination  on  Chapter  V 174 

APPENDIX  A.  —  Drawing  Room  System 

140.   Commercial  Drawing  Rooms 175 

Some  System  Usually  Required.  —  Value  of  Systematically  Carrying  on 
this  Work.  —  General  Method  of  Procedure.  —  Sizes  of  Drawings.  — 
Position  of  Sheet  or  Drawing  on  the  Board.  —  Border  Lines.  —  Number- 
ing and  Lettering  of  Sheets  and  Drawings.  —  Title-Form  and  Its  Loca- 
tion. —  Bill  of  Material  and  Its  Location.  —  Style  of  Lettering.  —  Con- 
ventions and  Abbreviations. 

INDEX  179 


ELEMENTS   OF  DRAWING 


CHAPTER  I 

SELECTION,    CARE   AND    USE    OF   DRAWING   INSTRU- 
MENTS  AND   MATERIALS 

i.  Introductory.  The  accuracy  and  finish  of  mechanical  and 
geometrical  drawings,  as  well  as  the  speed  with  which  the  drafts- 
man works,  depend  to  a  very  large  extent  upon  the  quality  of 
instruments  used.  To  secure  the  best  results  the  most  experienced 
draftsman  requires  instruments  of  a  first-class  quality,  and  as 
the  beginner  needs  all  the  assistance  possible,  he  should  not 
handicap  himself  by  using  instruments  of  an  inferior  grade. 
Since,  in  this  work,  a  knowledge  is  required  of  what  goes  to 
make  up  instruments  of  a  first-class  quality,  such  knowledge 
should  be  gained  before  purchases  are  made,  in  order  that  the 
fullest  benefits  may  be  obtained.  Thus  unsatisfactory  work, 
in  so  far  as  it  results  from  the  use  of  inferior  instruments  and 
supplies,  can  be  avoided. 

The  quality  of  an  instrument  must  not  be  judged  entirely  by 
its  cost,  but  by  its  design,  accuracy  of  workmanship,  and  the 
materials  from  which  it  is  made.  Some  of  the  more  costly  in- 
struments are  designed  for  extreme  accuracy  of  adjustment,  and 
are  so  delicate  in  mechanical  construction  that  ordinary  usage 
soon  renders  them  less  accurate  than  the  cheaper  but  more  sub- 
stantial makes.  Hence,  in  selecting  instruments  it  is  best  to 
avoid  those  of  extremely  delicate  construction,  for  as  a  rule 
instruments  of  simple  design  prove  most  satisfactory,  especially 
for  beginners. 

The  best  of  instruments,  however,  will  soon  deteriorate  and 
become  unsatisfactory  unless  properly  cared  for,  and  the  beginner 
is  especially  urged  to  cultivate  the  habit  of  seeing  that  his  instru- 
ments are  always  kept  in  the  best  shape  possible. 


OF  DRAWING 


In  the  following  paragraphs  instruments  are  briefly  described 
and  the  essential  points  which  determine  their  superiority  are 
noted.  Before  purchasing  instruments  read  the  first  portion  of 
each  item  referred  to  in  the  following  paragraph  and,  if  possible, 
consult  with  some  experienced  person  as  to  the  names  of  reliable 
makers  of  instruments  and  supplies. 

2.  List  of  Instruments  and  Supplies  Necessary  for  the  Com- 
plete Course: 

Drawing  Paper  (M)*.  10  sheets  of  drawing  paper  accurately 
cut  to  12"  X  18"  and  punched.  (See  page  4,  §  3.) 

Ruled  Paper  (L),  (S).  (a)  36  sheets  8"  X  loj"  standard 
punched  (for  #10  Manila  cover),  extra  heavy  weight  cross-section 
paper,  ruled  on  one  side  only  with  lines  £"  apart  and  every  eighth 
line  heavy.  (See  page  5,  §  4.)  (b)  (S)  6  sheets  8"  X  ioj" 
standard  punched  extra  heavy  weight  isometric  paper  ruled 
on  one  side  only.  (See  page  5,  §  4.) 

Tracing  Cloth  (M).  4  yards  i8|"-wide  tracing  cloth  of  best 
quality.  (See  page  6,  §  6.) 

Blue-print  Paper  (M).  J  yard  36"  wide  slow  acting  blue- 
print paper  of  best  quality.  Not  to  be  purchased  until  required. 
(See  page  6,  §  7.) 

Drawing  Boards  (M).  (a)  i  pine  drawing  board  19"  X  26". 
(See  page  7,  §  8.)  (b)  (L),  (S).  i  well  seasoned  pine  board 
10"  X  12"  X  TV  thick. 

Thumb  Tacks  (A),  i  dozen  thumb  jfe^cks  with  small  round 
heads  about  fV"  diameter.  (See  page  8,'§  9.) 

T-Square  (M).  i  T-square  with  solid  head  and  polished 
surfaces.  Blade  26"  long  and  preferably  having  edges  lined  with 
transparent  strips.  (See  page  8,  §  10.) 

Triangles  (M).  (a)  i  7"  transparent  triangle,  45°.  (See  page 
10,  §  n.)  (b)  i  10"  transparent  triangle,  3o°-6o°.  (See  page 
10,  §  ii.) 

Irregular  Curve  (M)  i  transparent  irregular  curve.  Similar 
to  K.  &  E.  #21  or  Dietzgen  #20.  (See  page  13,  §  12.) 

"  The  instruments  or  materials  marked  (L)  are  required  in  lettering; 
(M)  in  mechanical  drawing;  (S)  in  sketching;  (A)  in  all  courses. 


DRAWING  INSTRUMENTS  AND  MATERIALS  3 

Pencil  Pointer  (A),  i  medium-cut  file  (see  page  14,  §  13)  or 
a  small  pad  of  fine  sandpaper. 

Pencils  (A),  (a)  i  4.H  pencil  of  hexagon  cross  section.  (See 
page  14,  §  14.)  (b)  (M)  i  6H  pencil  of  hexagon  cross  section. 
(See  page  14,  §  14.) 

Erasers  (A),  (a)  i  block  of  "  Artgum  "  or  a  sponge  rubber. 
(See  page  16,  §  15.)  (b)  Faber's  (or  equivalent)  soft  green 
"Emerald"  eraser.  (See  page  16,  §  15.) 

Erasing  Shield  (A),  i  metal  or  celluloid  erasing  shield.  (See 
page  17,  §  16.) 

Soapstone  (A).  Small  piece  of  soapstone.     (See  page  18,  §  17.) 

Drawing  Ink  (A),  i  bottle  of  black  waterproof  drawing  ink- 
(See  page  18,  §  18.) 

Pens  (A),  (a)  i  each  of  D.  Leonardt  &  Co.'s  #506  F.  and  §516 
E.F.,  ball-pointed  pens,  (b)  i  each  of  Gillott  #170  and  #303; 
i  Esterbrook  #182  and  i  Spencerian  #i.  (See  page  18,  §  19.) 

Penholders  (A),  (a)  i  penholder  for  ball-pointed  pens.  (See 
page  20,  §  20.)  (b)  i  penholder  for  ordinary  pens.  Cork- tipped 
holders  preferred. 

Drawing  Instruments  (M).  i  set  of  drawing  instruments 
of  good  design  and  quality,  consisting  of  at  least  the  following: 

(a)  Ruling  pen,  5"  instrument  of  best  quality.     (See  page  20, 

§21.) 

(b)  Compass,  5",  pivot-jointed  instrument  (see  page  23,  §  22) 
with  handle,  lengthening  bar,  detachable  pencil  and  pen  legs. 

(c)  Dividers,  5"  instrument  with  hair-spring  adjustment.    (See 
page  26,  §  23.) 

(d)  Bow  dividers  having  a  maximum  capacity  of  ij"  radius. 
(See  page  27,  §  24.) 

(e)  Bow  pencil  having  a  maximum  capacity  of   ij"  radius. 
(See  page  27,  §  25.) 

(f)  Bow  pen  of  best  quality  and  having  a  maximum  capacity 
of  i|"  radius.     (See  page  28,  §  26.) 

(g)  Case  for  set  of  drawing  instruments. 

Scale  (M),  (S).  i  architect's  1 2-inch  triangular  boxwood 
drawing  scale,  graduated  as  follows:  |",  i",  f",  |",  f",  i",  ij", 
2",  3",  4",  and  one  "  edge  "  graduated  in  inches  and  sixteenths  of 
an  inch.  (See  page  29,  §  27.) 


4  ELEMENTS  OF  DRAWING 

Protractor  (M).  Not  absolutely  necessary  in  this  course. 
(See  page  31,  §  28.) 

Machinist's  Calipers  (S).  (a)  i  pair  6"  outside  spring-cali- 
pers. (See  page  32,  §  29.)  (b)  i  pair  6"  inside  spring- 
calipers. 

Machinist's  Scale  (S).  i  2-foot  length  machinist's  scale. 
Not  absolutely  necessary  in  this  course.  (See  page  32,  Fig.  36.) 

Machinist's  Dividers  (S).  i  pair  6"  machinist's  dividers. 
Not  absolutely  necessary  in  this  course.  (See  page  33,  §  29.) 

Blotter,     i  ordinary  4"  X  9"  blotter.     (See  page  33,  §  30.) 

Pen  Wiper  (A),  i  piece  of  linen  cloth  about  9"  X  9". 
(See  page  33,  §  30.) 

Instrument  Cleaner  (A),  i  piece  of  cotton  cloth  about 
1 8"  X  1 8"  for  brushing  off  drawings  and  cleaning  instruments. 
(See  page  33,  §  30.) 

Manila  Covers  (L),  (S).     3  standard  (#10)  Manila  covers. 

Paper  Fasteners  (A),  i  dozen  #3  brass  paper  fasteners  with 
washers. 

Carbonate  of  Soda  (M).  Small  quantity  of  soda  for  making 
changes  on  blue-print  paper. 

3 .  Drawing  Paper.  In  selecting  paper  to  use  for  any  particular 
drawing,  the  character  of  the  work  and  the  purpose  for  which  the 
drawing  is  to  be  made  are  the  determining  factors. 

In  general  a  good  drawing  paper  should  be  tough,  strong,  and 
of  uniform  thickness.  It  should  not  become  brittle  or  discolored 
with  age,  and  should  not  wrinkle  nor  warp  during  changing 
weather.  The  surface  should  stretch  evenly  and  admit  of  con- 
siderable erasing  without  injury. 

For  inked  drawings,  the  surface  of  the  paper  selected  should 
neither  repel  nor  absorb  liquids.  If  the  paper  repels  ink  the 
lines  will  be  irregular  and  uneven.  An  illustration  of  this  is 
seen  if  an  inked  line  is  drawn  on  oily  paper.  If  the  paper 
absorbs  ink,  the  line  will  spread  and  resemble  a  line  drawn  upon 
blotting  paper.  For  pencil  drawings,  paper  with  an  unpolished 
surface  should  be  selected,  since  it  will  take  a  pencil  mark  more 
readily  than  paper  with  a  polished  surface  and  does  not  require 
the  same  care  in  making  erasures.  There  is  little  difference  in 


DRAWING   INSTRUMENTS   AND   MATERIALS 


the  two  sides  of  good  drawing  paper,  but  the  side  from  which  the 
"water-mark"  reads  correctly  is  meant  to  be  the  working  side. 

A  cheap  grade  of  Manila  paper  will  do  for  such  pencil  work  as 
.shop  drawings,  preliminary  sketches,  drawings  to  be  traced,  and 
in  general  all  drawings  not  requiring  extreme  accuracy  nor 
intended  to  be  of  permanent  value.  A  better  grade  of  paper 
should  be  used  for  work  of  a  more  exacting  character. 

Whatman  paper  is  used  extensively  for  making  permanent  ink 
drawings.  There  are  two  grades  suitable  for  this  purpose; 
namely,  hot  pressed  and  cold  pressed.  The  hot  pressed 
(marked  H.P.)  has  a  smooth  surface,  and  is  used  principally  for 
fine-line  drawings.  The  cold  pressed  (marked  N.  to  signify  not 
hot  pressed,  and  sometimes  marked  C.P.)  is  used  extensively  for 
tinted  and  water-color  work. 

4.  Ruled  Paper.  In  the  study  of  free-hand  lettering  and  in 
sketching,  the  beginner  can  save  much  time  and  secure  greater 
accuracy  by  using  specially  ruled  paper,  the  advantage  being 
that  proportion  can  be  obtained  without  the  aid  of  measuring 
instruments. 

Fig.  i  (a)  shows  cross-section  ruling,  the  small  squares  being 
one-eighth  inch, 
and  every  eighth 
line  is  extra 
heavy  so  that  the 
one-inch  squares 
stand  out  promi- 
nently. This 
paper  is  used  in 
ordinary  sketch- 
ing, etc. 


(a)  Cross-Section  Ruling.  (b)  Isometric  Ruling. 

Fig.  i.  — Ruled  Paper. 

Fig.  i  (b)  shows  isometric  ruling,  which  is  used  in  making 
isometric  perspective  sketches. 

Care  must  be  exercised  in  cleaning  drawings  made  on  cross- 
section  paper,  as  cleaning  with  either  the  eraser  or  the  "artgum" 
tends  to  dim  the  section  lines  and  thus  spoil  the  work. 

Make  all  lines  light  weight  and  with  a  medium  soft  pencil 
then  retrace  the  lines  that  are  to  be  permanent  and  clean  the 
drawing.  This  method  insures  the  least  amount  of  erasing. 


6  ELEMENTS  OF  DRAWING 

5.  Tracing  Paper.     Tracing  paper  is  a  thin,  transparent  paper 
which  is  used  for  making  tracings  that  are  usually  (but  not 
always)  to  be  of  a  temporary  character.     It  is  cheaper  than 
tracing  cloth,  but  inferior  to  it  in  permanency.     Blue  prints 
made  from  drawings  on  tracing  paper  require  longer  exposure 
and  are  not  so  distinct  as  those  made  from  drawings  on  tracing 
cloth. 

6.  Tracing  Cloth.     Tracing  cloth  is  a  specially  prepared  linen, 
having  one  side  finished  with  a  smooth  glazed  surface  and  the 
other  dull  finished.     Either  side  will  take  ink  and  there  is  a  differ- 
ence of  opinion  among  draftsmen  as  to  which  is  the  better  side  to 
work  on.     The  glazed  side  is  better  for  lettering  and  free-hand 
work  in  general,  as  there  is  less  tendency  to  catch  the  pen  point 
and  cause  blotting;  also,  since  the  glazed  coating  holds  the  ink 
and  keeps  it  from  soaking  into  the  fibers  of  the  cloth,  it  is  easier 
to  erase  ink  from  this  side.     The  chief  disadvantages  are  that 
the  glazed  side  does   not  take  the  ink  quite  so  readily;  also 
the  tracing  tends  to  curl  up  when  the  inking  has  been  done  on 
the  glazed  side.     The  dull  side  takes  ink  more  easily,  and  if  any 
lines  are  to  be  penciled  directly  on  the  cloth  (as  in  making  alter- 
ations, additions,  etc.)  the  rough  surface  of  the  dull  side  takes 
these  lines  more  readily.     For  the  same  reason  the  dirt  collects 
from  the  triangles  and  T-square.     The  glazed  side  is  recom- 
mended for  beginners  and  with  experience  the  draftsman  will 
determine  his  preference. 

In  cutting  the  tracing  cloth  (called  for  in  the  list  of  neces- 
sary supplies)  into  sheets  for  use,  see  that  each  sheet  is  large 
enough  to  permit  of  cutting  off  the  margin  containing  the  thumb 
tack  holes  when  the  tracing  is  finally  trimmed  to  the  standard 
size  (12"  X  18").  Also,  in  cutting  the  cloth,  care  must  be  exer- 
cised to  avoid  breaking  its  surface,  as  creases  and  broken  places 
render  the  cloth  unfit  for  use. 

Only  a  good  quality  tracing  cloth  should  be  used. 

*• 

7.  Blue-print  Paper  is  a  specially  prepared  paper,  having  one 
side  coated  with  chemicals  which  are  sensitive  to  light  and  which 
will  turn  a  rich  permanent  blue  after  the  paper  has  been  exposed 


DRAWING  INSTRUMENTS  AND  MATERIALS  7 

to  the  light  and  washed  in  clean  water.  Blue-print  paper  is 
seldom  prepared  in  the  drafting  room  since  it  can  be  bought 
cheaper  in  the  open  market.  A  formula  for  preparing  blue-print 
paper  is  as  follows : 

2\  ounces  Red  Prussiate  of  Potassium  in  i  pint  of  water. 

4  ounces  Citrate  of  Iron  and  Ammonia  in  i  pint  of  water. 

Dissolve  thoroughly  and  filter;  then  mix  and  apply  evenly  on 
one  side  of  the  paper  with  a  sponge  or  a  broad,  thin  brush.  The 
paper  must  be  prepared  in  a  dark  place  and  must  be  stored  in 
a  dark  dry  place. 

8.  Drawing  Boards.  A  drawing  board  should  be  made  of  a 
light  weight  material  which  is  not  greatly  affected  by  changes  of 
weather,  and  which  will  take  the  thumb  tacks  easily  and  hold 
them  securely.  Also,  the  board  should  be  designed  to  allow  for, 
or  resist  as  far  as  possible,  any  change  in  shape  due  to  warping  or 
handling.  The  best  material  for  a  drawing  board  is  thoroughly 
seasoned,  soft,  white  pine,  free  from  knots  or  pitch.  The  best 
design  depends  largely  on  the  size  of  the  board. 

The  board  recommended  for  use  in  this  work,  both  as  to 
design  and  size,  is  shown  in  Fig.  2.  This  board  consists  of  a 


Fig.  2.  —  Ordinary  Drawing  Board. 

central  portion  or  "  body,"  in  which  part  the  grain  should  run 
lengthwise,  and  "  end  strips  "  so  placed  that  the  grain  runs  at 
right  angles  to  that  of  the  body. 

The  body  and  end  strips  are  united  by  a  glued  tongue  and 
grooved  joint.  In  some  instances  the  end  strips  are  made  of 
hard  wood  in  order  to  better  resist  warping  or  being  nicked  in 
handling.  This  construction  will  resist  excessive  warping  in 


&  ELEMENTS  OF  DRAWING 

small  boards,  but  the  larger  sizes  are  usually  made  with  a  pair 
of  hard-wood  ledges  screwed  or  dovetailed  to  the  back,  and  in 
addition  there  is  a  series  of  saw  grooves  cut  lengthwise  on  the 
back  of  the  body  of  the  board. 

The  drawing  board  should  be  covered  with  a  light  coat  of 
shellac  to  protect  it  from  moisture  and  to  keep  it  clean. 

The  top  surface  is  termed  the  working  face  (see  Fig.  2, 
page  7),  and  should  be  a  perfectly  smooth  plane.  The  left-hand 
edge  is  termed  the  working  edge,  because  it  acts  as  a  guide  for 
the  T-square  head.  The  working  edge  should  be  perfectly 
straight  and  smooth  and  free  from  nicks.  The  straightness  of 
the  working  edge  should  be  tested  occasionally  by  placing  a 
standard  straightedge,  or  the  edge  of  a  T-square  blade  which  is 
known  to  be  perfectly  straight,  along  it  to  see  if  the  two  coin- 
cide throughout. 

9.  Thumb  Tacks.     For  all  ordinary  work  the  drawing  paper 
or  tracing  cloth  is  secured  to  the  drawing  board  with  thumb 

tacks.     These  tacks  are  inexpensive  and  only  the 
best  should  be  used.    A  good  form  is  shown  in 

Fig.  3- 

The  tack  should  be  small  and  the  outer  edge 
of  the  "  head  "  should  be  thin  so  as  not  to  inter- 
•^  \r"'^**'    fere  with  the  free  use  of  the  T-square  and  triangles; 
i  as  a  rule,  small  thumb  tacks  are  preferable,  say  T6g  " 

Fig.  3.  —  ordinary  diameter. 

One  tack^  should  be  used  at  each  corner  of  the 
sheet,  and  if  the  drawing  of  tracing  is  large,  enough  thumb  tacks 
should  be  placed  along  the  edges  to  hold  the  paper  or  cloth 
securely  on  the  drawing  board.  Tracing  especially  can  be  done 
much  more  rapidly  if  the  cloth  fits  closely  to  the  paper  drawing. 

10.  T-Squares.     The  T-square  derives  its  name  from  its  resem- 
blance to  the  letter  T  and  from  its  use  in  "  squaring  "  the  paper 
on  the  drawing  board.     It  is  intended  primarily  to  serve  as  a 
ruling  edge  in  drawing  horizontal  lines  (that  is,  lines  perpendicular 
to  the  working  edge  of  the  drawing  board),  and  to  provide  an 
edge  for  guiding  the  triangles  in  drawing  vertical  or  inclined  lines. 


DRAWING  INSTRUMENTS  AND   MATERIALS  9 

In  its  simplest  form  (see  Fig.  4)  the  T-square  consists  of  a  thin 
"blade"  securely  fastened  at  right  angles  to  a  thicker  and  shorter 
piece  termed  the  "  head." 


Fig.  4.  —  Ordinary  T-Square. 

In  a  more  elaborate  design  the  head  is  pivoted  so  that  it  can 
be  adjusted  and  fastened  at  any  angle  with  the  blade.  This 
arrangement  enables  the  draftsman  to  use  the  working  edge  of 
the  drawing  board  to  guide  the  T-square  in  drawing  a  series  of 
parallel  lines  that  are  not  perpendicular  to  that  edge.  While 
this  "swivel  head"  is  sometimes  an  advantage,  it  is  not  neces- 
sary for  ordinary  use  and  the  design  shown  in  Fig.  4  is 
recommended. 

T-squares  are  made  of  wood,  rubber  and  metal,  the  most  satis- 
factory being  made  of  wood  and  having  the  edges  of  the  blade 
lined  with  a  narrow  strip  of  transparent  amber  or  celluloid.  The 
blade  should  be  as  long  as  the  drawing  board,  and  it  is  desirable 
to  have  the  blade  and  the  head  exactly  at  right  angles  in  order 
that  the  lines  drawn  with  the  T-square  will  be  at  right  angles 
to  the  working  edge  of  the  drawing  board.  This,  however, 
is  not  absolutely  necessary,  for  if  the  working  edge  is  straight 
and  the  T-square  is  properly  used,  the  lines  are  always  drawn 
with  reference  to  the  working  edge  of  the  board,  and  are  there- 
fore parallel,  and  the  drawing  will  be  accurate. 

The  T-square  should  be  polished  or  given  a  coat  of  shellac  in 
order  that  dirt  may  not  adhere  to  its  surface;  for  unless  the 
blade  is  perfectly  clean  it  will  soon  soil  the  drawing  in  rubbing 
over  it. 

To  test  the  straightness  of  the  working  edge,  use  a  pencil 
having  hard  lead  sharpened  to  a  fine  chisel  edge  (see  page  15,  §  14) ; 
hold  it  against  the  working  edge  of  the  T-square  and  draw  a  line 
the  full  length  of  the  blade.  Turn  the  blade  over  (i.e.,  revolve 
about  the  lines  just  drawn)  so  as  to  bring  the  opposite  side 
against  the  paper,  and  if  the  working  edge  does  not  coincide  with 


10  ELEMENTS  OF  DRAWING 

the  line  throughout  its  entire  length,  this  edge  is  not  "true." 
The  inside  edge  of  the  T-square  head  may  be  tested  by  apply- 
ing any  standard  straightedge  to  it. 

Care  must  be  taken  that  the  blade  is  not  loosened,  and  that 
the  working  edges  are  perfectly  straight  and  free  from  nicks. 
The  T-square  must  not  be  used  to  hammer  thumb  tacks  into 
place,  and  the  top  or  working  edge  of  the  blade  must  never  be 
used  to  guide  the  knife  in  cutting  paper  or  tracing  cloth,  as  the 
smallest  nick  will  disfigure  all  lines  drawn  by  the  aid  of  that 
portion  of  the  blade.  The  lower  edge  of  the  T-square,  however, 
may  be  used  as  a  straightedge  for  trimming  drawings  or  cutting 
paper. 

To  use  the  T-square,  hold  it  near  the  center  of  the  head  with 
the  left  hand,  and,  with  a  steady  but  unstrained  grip,  slide  the 
inner  face  of  the  head  along  the  working  edge  of  the  drawing 
board  until  the  top  edge  of  the  blade  is  in  the  proper  position  for 
drawing  the  line  or  guiding  the  triangle.  The  lower  edge  of 
the  blade  should  never  be  used  in  this  way,  as  it  may  not  be 
parallel  to  the  working  edge,  and  as  a  result  all  lines  drawn 
would  not  be  parallel. 

The  habit  should  be  cultivated  of  "feeling"  that  the  T-square 
is  in  perfect  contact  before  drawing  a  line.  That  is,  the  head 
should  set  firmly  against  the  working  edge  of  the  drawing  board 
and  the  blade  should  lie  perfectly  flat  on  the  drawing. 

ii.  Triangles.  Triangles  are  used  as  a  guide  for  the  ruling  pen 
or  the  pencil  in  drawing  lines  at  an  angle  to  the  T-square  blade. 
All  the  angles  of  a  triangle  must  be  true  and  its  edges  straight 
and  free  from  nicks.  The  material  of  which  it  is  made  should 
not  warp  easily,  or  show  tendency  to  gather  and  hold  dust;  it 
should  be  light  enough  to  be  easily  handled  and  hard  enough  to 
hold  its  edge  under  use.  Triangles  are  made  of  wood,  rubber, 
amber,  celluloid,  or  metal.  Metal  triangles  are  accurate  and 
durable,  but  are  difficult  to  handle,  and  if  dropped  on  a  drawing 
the  corners  puncture  the  surface.  Those  made  of  wood  are 
cheap  and  light  in  weight,  but  warp  easily  and  are  hard  to 
keep  clean.  The  triangles  made  of  transparent  amber  or  cellu- 
loid meet  most  of  the  requirements  of  a  first-class  instrument 


DRAWING  INSTRUMENTS  AND  MATERIALS  n 

and  are  to  be  preferred.  An  additional  advantage  is  that,  due 
to  their  transparency,  the  draftsman  is  enabled  to  see  work 
already  completed  although  it  may  be  covered  with  the  triangle. 
The  triangles  most  generally  used  are  the  45°  [see  Fig.  5  (a)]  and 
the  3o°-6o°,  or  what  is  generally 
called  the  60°,  triangle  [see  Fig. 


The  most  desirable  size  of  tri- 
angle to  use  depends  largely  on 
the  work  to  be  done,  but  the 
working  edges  should  be  long  (a)  4'5o  Tdangle;  (b>  6oo'  Triangle> 

enough    not    tO    require    Working  Fig.  5.-  Ordinary  Triangles. 

too  close  to  the  corners,  since  they  become  rounded  with  use 
and  are  therefore  inaccurate.  Accuracy  in  triangles  is  of  the 
greatest  importance  and  they  should  be  tested  when  purchased 
as  well  as  occasionally  thereafter,  as  they  may  lose  their 
accuracy  by  use.  In  testing  the  accuracy  of  the  triangles, 
use  a  6H  pencil  with  lead  sharpened  to  a  fine  chisel  edge.  (See 
page  15,  §  14).  All  edges  of  the  triangle  should  be  first  tested 
for  straightness  by  holding  them  against  an  accurate  straight- 
edge, or  by  the  method  given  for  testing  the  T-square  blade  (see 
page  9,  §  10)  and  then  the  angles  should  be  tested. 

To  test  the  90°  angle  for  accuracy,  place  one  of  the  short  sides 
of  the  triangle  against  the  working  edge  of  the  T-square  blade 
and,  with  the  chisel  edge  of  the  pencil  held  close  to  the  triangle, 
draw  a  vertical  line.  Next  turn  the  triangle  over  (i.e.,  revolve 
it  about  the  line  just  drawn)  so  as  to  bring  the  opposite  side 
against  the  paper,  and,  using  the  same  edge  as  a  guide  for  the 
pencil,  draw  a  second  vertical  line  through  a  point  at  either  ex- 
tremity of  the  first  line.  If  these  two  lines  do  not  coincide 
throughout,  the  90°  angle  is  not  accurate. 

To  test  the  45°  angle  for  accuracy,  place  one  of  the  short  edges 
of  the  triangle  against  the  working  edge  of  the  T-square  blade, 
and,  using  the  longest  edge  of  the  triangle  as  a  guide  for  the  pencil, 
draw  a  line.  Next  turn  the  triangle  over  so  as  to  bring  the 
opposite  side  against  the  paper,  and  revolve  it  until  the  second 
short  edge  is  against  the  working  edge  of  the  T-square  blade,  and, 
again  using  the  long  edge  of  the  triangle  as  a  guide  for  the  pencil, 


12 


ELEMENTS  OF  DRAWING 


draw  a  second  line  through  a  point  at  either  extremity  of  the 
first.  If  the  two  lines  do  not  coincide  throughout,  the  45°  angle 
is  not  accurate. 

To  test  the  30°  and  60°  angles  for  accuracy,  draw  a  horizontal 
line  with  the  T-square,  then  place  the  shortest  side  of  the  tri- 
angle against  the  working  edge  of  the  T-square  blade,  and,  using 
the  longest  edge  as  a  guide  for  the  pencil,  draw  a  line  to  intersect 
the  first  line.  Next  turn  the  triangle  over  (i.e.,  revolve  it 
about  the  line  drawn)  so  as  to  bring  the  opposite  side  against  the 
paper;  with  the  same  short  side  against  the  T-square,  again  use 
the  longest  edge  as  a  guide  for  the  pencil,  and  construct  a  triangle 
by  drawing  a  third  line  to  intersect  the  other  two.  If  all  three 
sides  of  the  triangle  drawn  are  not  of  equal  length,  the  30°  and  60° 

angles  are  not  accurate. 
Fig.  6  shows  the 
method  of  using  the 
triangle  in  connection 
with  the  T-square,  the 
left  hand  manipulating 
and  holding  the  triangle 
and  the  T-square. 

The  draftsman  should 
arrange  his  work  so  as  to  avoid  being  in  a  strained  position, 
and  the  light  should  come  from  a  direction  that  will  not  cause 
the  T-square  and  triangle  to  cast  a  shadow  along  the  edges 
being  used  as  a  guide  to  the  pen  or  pencil. 


Fig.  6.  —  Using  the  Triangle  in  Connection  with 
the  T-square. 


Fig.  7.  —  Exact  Angles  that  can  be  drawn,  using  Triangles  and  T-Square. 

Fig.  7  shows  the  angles  that  can  be  accurately  drawn  by  using 
the  60°  and  45°  triangles  and  T-square. 


DRAWING  INSTRUMENTS  AND   MATERIALS 


A  triangle  should  not  be  used  alone  in  drawing  lines  parallel  or 
at  a  given  angle  with  one  another,  but  should  be  guided  by  the 
working  edge  of  the  T-square  or 
another  triangle.  Fig.  8  shows 
the  method  of  drawing  parallel 
lines,  using  one  triangle  as  a 
guide  for  the  other.  In  a  sim- 
ilar manner  the  T-square  blade 

,          ,  .  Fig.  8.  — Drawing  Parallel  Lines  using  one 

Can     also     be     USed     as     a    gUlde  Triangle  as  a  guide  to  another. 

for    the    triangle  to   draw   a   series  of    parallel    lines    at   any 
angle. 

12.  Irregular  Curves.     The  irregular  or  French  curves  are 
used  as  a  guide  to  the  pen  or  pencil  in  drawing  curved  lines  that 
cannot  be  conveniently  or  accurately  made  with  the  compasses. 
French  curves  are  made  of  the  same  materials  as  triangles, 
and  the  remarks  on  materials  for  triangles,  therefore,  apply  to 
French  curves  (see  page  10,  §11).     They 
may  be  had  of  many  different  shapes,  but 
those  shown  in  Fig.  9  probably  have  the 
widest  use. 

To  use  the  French  curve,  locate  a  series 
of  points  on  the  line  to  be  drawn,  and 
carefully  sketch  a  very  light  free-hand 
pencil  line  through  them;  next  place  the 
French  curve  so  that  its  edge  coincides  with  the  longest  segment 
of  the  free-hand  line  possible,  and  draw  this  segment  of  the  line 
by  using  the  edge  of  the  curve  as  a  guide.  The  French  curve 
is  then  shifted  to  coincide  with  another  part  of  the  line  and  the 
process  repeated  until  the  entire  curve  is  drawn.  Great  care 
must  be  taken  that  the  segments  are  well  joined  and  that  the 
entire  line  appears  uniform  and  continuous.  In  inking  such 
a  curved  line,  the  blades  of*  the  pen  must  at  all  times  be 
tangent  to  the  curve;  otherwise  the  line  will  not  be  of  uniform 
width.  In  drawing  an  irregular  curve,  especially  when  inking, 
it  is  best  to  first  leave  a  slight  break  between  segments  and  then, 
by  a  separate  operation,  join  all  segments  so  that  the  curve  is 
continuous  and  the  joined  points  do  not  show. 


Fig.  9.  —  Ordinary  Irregular 
(French)  Curves. 


14  ELEMENTS   OF   DRAWING 

13.  Pencil    Pointer.     A   small    medium   cut    file,    with   the 
end  flattened  to  an  edge  and  curved  (see  Fig.  10),  serves  the 

double  purpose  of  a  tack  lifter 
and  pencil  pointer. 

Fig.  10. -Combination  Pencil  Sharpener  Jn  USinor  the   file    it    should   be 

and  Tack  Lifter. 

frequently  tapped  to  remove  the 

lead  filings.  While  filing  the  lead  or  tapping  the  file,  care 
must  be  taken  that  the  filings  do  not  fall  on  and  smear  the 
drawing. 

14.  Lead  Pencils.     The  essential  qualities  of  a  good  pencil 
depend  somewhat  on  the  work  to  be  done,  but  the  lead  should 
always  be  smooth  and  free  from  grit,  making  a  clear-cut,  distinct 
mark  as  sharp  as  an  inked  line,  yet  one  which  can  be  easily  and 
completely  erased.     To  meet  all  requirements  lead  is  made  in 
different  degrees  of  hardness,  and  the  grade  selected  will  depend 
upon  the  kind  of  work  to  be  done  and  the  nature  of  the  surface 
on  which  the  drawing  is  made.     Should  the  lead  be  too  soft,  the 
lines  will  smear,  especially  if  the  drawing  is  subjected  to  con- 
siderable handling;  whereas  if  the  lead  is  too  hard,  considerable 
pressure  on  the  pencil  point  is  necessary  to  make  a  visible  line. 
This  indents  the  paper,  anot  erasing  and  changing  of  such  lines 
are  difficult  and  unsatisfactory. 

Manufacturers  usually  indicate  the  degree  of  hardness  of  the 
lead  in  a  drawing  pencil  by  the  capital  letter  H,  which  is  repeated 
as  often  as  necessary;  thus,  an  H  pencil  is  the  softest,  then  comes 
HH,  then  HHH,  etc. 

The  HHHH  (called  4H)  pencil  is  a  satisfactory  grade  for  such 
work  as  putting  in  dimensions,  arrowheads,  lettering,  making 
sketches,  and  in  general  for  free-hand  work. 

The  6H  pencil  is  a  satisfactory  grade  for  making  mechanical 
drawings. 

The  degree  of  hardness  of  the  lead  in  some  cases  is  indicated 
by  a  number,  beginning  with  No.  i  for  the  softest,  the  numbers 
progressing  as  the  degree  of  hardness  increases. 

Drawing  pencils  of  either  a  hexagonal  or  round  cross  section 
are  made  but  the  hexagonal  pencil  is  to  be  preferred  since  it  is 
not  so  liable  to  roll  off  the  drawing  board. 


DRAWING  INSTRUMENTS  AND   MATERIALS 


To  do  satisfactory  work  the  pencil  must  be  kept  well  sharpened, 
and  it  is  important  that  the  beginner  learn  the  best  method  of 
keeping  the  pencil  in  condition.  The  lead  may  be  given  either 
the  round  "cone  point"  or  the  flat  "chisel  edge."  Each  of  these 
forms  has  its  particular  use  and  it  is  often  an  advantage  to  have 
both  ends  of  a  pencil  sharpened,  one  end  having  the  cone  point, 
the  other  the  chisel  edge. 

The  cone  point  is  used  by  many  draftsmen  for  all  ordinary 
drawing,  and  is  absolutely  necessary  for  lettering,  dimensioning, 
locating  points  on  a  drawing,  and  all  free-hand  work. 

The  following  method  of  sharpening  a  pencil  gives  a  point 
that  will  "  stand  up  "  well  under  use. 

With  a  sharp  knife,  make  a  long,  sloping  cut  (about  seven- 
eighths  inch  in  length),  removing  sufficient  wood  to  expose  a 
cylinder  of  lead,  say,  about  three- 
eighths  inch  long.  (See  Fig. 
n). 

Hold  the  pencil  at  an  angle 
with  the  surface  of  a  file  (or  a 
piece  of  fine  sandpaper),  and 
draw  the  lead  across  the  rough 
surface,  at  the  same  time  ro- 
tating the  pencil  in  such  a  way 
that  the  lead  is  worn  to  a  cone  shape  of  the  longest  slope  pos- 
sible, but  do  not  file  to  a  sharp 
point. 

Next  raise  the  pencil  to  an 
angle  of  about  15°  and  file 
the   end   of    the   lead    away 
until    pointed.      The    pencil 
point  should  then  appear  as  shown  in  Fig.  12. 

A  few  strokes  across  the  file  at  frequent  intervals  will  keep 
the  pencil  lead  in  good  working  condition,  and  the  long  slope 
of  the  lead  saves  cutting  away  the  wood  every  time  the  pencil 
point  is  sharpened. 

The  disadvantage  of  a  cone  point  is  that  it  wears  away  very 
rapidly,  and  to  be  kept  in  good  shape  must  be  frequently  re- 
pointed.  When  a  number  of  long,  continuous  lines  are  to  be 


Fig.  ii.  — Pencil  sharpened  to  Lead 
Cylinder  only. 


Fig.  12.  — Pencil  Lead  sharpened  to  Long 
Cone  and  to  Point. 


i6 


ELEMENTS   OF  DRAWING 


drawn,  many  draftsmen  prefer  to  use  a  chisel  edge  (see  Fig.  14). 
To  form  a  chisel  edge  cut  away  the  wood  as  explained  above. 
Next  hold  the  pencil  so  it  will  not  rotate,  and  at  such  an  angle 
that  by  drawing  it  across  the  file  the  lead  is  worn  to  a  bev- 
eled surface  of  the  longest  slope  possible.  Do  not  file  to  the 
center  of  the  lead  before  turning  the  pencil  over  to  file  a  similar 
beveled  surface  on  the  reverse  side  (see  Fig.  13).  At  this  stage 
the  pencil  should  not  have  a  sharp  edge. 
Next  raise  the  pencil  to  an  angle  of  about 
15°,  and  by  moving  back  and  forth,  at  the 
same  time  slightly  rolling,  file  the  tip  on 
one  side,  and  then  on  the  other  side,  until 
a  rounded  chisel  edge  is 
produced.  (See  Fig.  14.) 
The  lead  point  must 
never  be  moistened,  as 
lead  softens  from  mois- 
ture, and  then  produces 
Fig.i3.— Pencil  Lead  sharp- a  smeared  line  which 

ened  to  Rough  Chisel  Form  t   fe      satisfactorily 

but  not  to  Edge.     (Front  J 

and  Side  View.)  erased. 

To  put  a  chisel  edge  on  the  lead  of  the 
bow  pencil  or  compass,  fasten  the  lead  in 
the  instrument  so  that  it  projects  about  one  Fie- 14.— Pencil  Lead  sharp- 

.  .       ,  .    -.  ,  .      .  ened   to    Working    Chisel 

quarter  of  an  inch,  and  file  to  a  chisel  edge    Edge.    (Side  and  Front 
as  explained  above,  always  keeping  the  edge     View>) 
of  the  lead  perpendicular  to  the  radius  of  the  instrument,  that 
is,  tangent  to  the  arcs  to  be  drawn. 

15.  Erasers  and  Erasures.  Erasers  are  used  for  removing 
pencil  or  ink  lines  and  for  cleaning  the  drawing. 

The  pencil  eraser  should  be  made  of  soft,  fine-grained  rubber, 
free  from  sand  or  grit,  and  of  a  texture  that  will  not  glaze,  smear, 
or  injure  the  surface  of  the  drawing. 

The  ordinary  ink  eraser  is  hard  and  gritty  but  should  be  flexible. 
Ink  erasers  often  contain  so  much  grit  that  they  injure  the  surface 
of  the  drawing,  and  for  this  reason  many  draftsmen  prefer  a  fine- 
grained, soft  eraser  that  can  be  used  for  both  pencil  and  ink  erasing. 


DRAWING  INSTRUMENTS  AND   MATERIALS  17 

For  cleaning  drawings  sponge  rubber,  kneaded  rubber,  and 
"  artgum  "  are  used.  The  eraser  should  be  entirely  free  from 
grit  and  soft  enough  to  wear  away  rapidly,  so  that  it  will  not 
mar  or  scratch  the  surface  of  the  paper  or  injure  the  lines  of  the 
drawing  and  will  constantly  present  a  clean  rubbing  surface. 

In  making  an  erasure,  rub  over  the  line  with  a  light  pressure 
until  it  disappears;  then  brush  off  the  particles  of  rubber  and 
paper  with  a  clean  rag  so  that  the  drawing  will  not  become 
smeared.  Beginners  are  liable  to  press  too  heavily  when  erasing, 
thinking  thereby  to  save  time.  This  should  not  be  done  as  it 
injures  the  surface  of  the  drawing.  Neither  should  erasing  be 
done  so  rapidly  that  the  colored  rubber  heats  and  streaks  the 
work.  The  surface  of  the  drawing  is  liable  to  injury  if  a  knife 
edge  is  used  to  scratch  out  lines.  If  the  surface  of  the  paper 
or  cloth  is  injured  in  erasing,  it  can  be  improved  by  rubbing 
briskly  over  the  injured  area  (which  must  be  perfectly  clean) 
with  a  smooth,  hard  surface  (such  as  the  bone  handle  of  a  pocket- 
knife)  until  the  surface  has  become  smooth.  Soapstone  may 
also  be  effectively  used  for  this  purpose.  (See  page  18,  §  17.) 

An  eraser  should  be  perfectly  clean  when  used,  and  if  the 
rubbing  surface  does  not  wear  off  fast  enough  to  keep  clean,  the 
eraser  end  should  be  rubbed  upon  some  clean  spot  of  the  draw- 
ing board  until  it  is  free  from  dirt. 

Never  attempt  to  make  an  erasure  on  a  drawing  which  is 
not  securely  fastened  with  thumb  tacks,  for  if  held  down  only 
with  the  fingers,  the  drawing  frequently  slips  and  it  is  liable  to 
be  spoiled  by  being  creased  or  wrinkled. 

As  little  erasing  as  possible  should  be  done  when  making  a 
drawing  to  avoid  injuring  the  drawing  surface. 

1 6.  Erasing  Shield.  When  erasing  a  line,  letter,  or  dimension, 
care  must  be  taken  that  the  surrounding  /—  —^ 

work  is  not  injured.     To  prevent  injury, 
thin  sheets  of  flexible  metal  or  transparent          0 
celluloid,  provided  with  slots  and  holes  of    I       c 
various  shapes  and  sizes,  are  used  to  protect   Fig.  I5._  ordinary  Erasing 
the  drawing  while  making  erasures  over  a  Shield, 

limited  area  through  these  openings.    Fig.  15  shows  the  ordinary 


1 8  ELEMENTS  OF  DRAWING 

form  of  erasing  shield.  It  is  important  that  the  shield  always 
be  kept  clean  on  both  sides,  otherwise  when  using  it  the  drawing 
is  liable  to  become  smeared. 

17.  Soapstone.     Soapstone   is   a  soft   mineral  (a  compact, 
granular  variety  of  talc)  which  gets  its  name  because  of  its 
soapy  feel.     If  the  surface  of  paper  or  tracing  cloth  has  been 
injured  in  erasing,  it  may  be  improved  by  rubbing  soapstone 
over  the  injured  portion  and  polishing  with  a  clean,  dry  rag. 

18.  Drawing  Ink.     Drawing  ink  differs  from  the  ordinary 
ink  used  for  writing,  in  that  it  is  heavier  and  has  no  penetrating 
qualities,  but  merely  lies  upon  the  surface  of  the  paper  or  cloth. 

The  requirements  of  a  good  drawing  ink  are  that  it  will  flow 
freely,  dry  readily,  and  will  not  gum;  it  must  contain  no  chemicals 
that  will  have  an  injurious  effect  upon  the  instruments  or  paper, 
and  it  must  be  absolutely  waterproof.  To  be  waterproof  means 
that  the  ink  will  not  redissolve  after  drying,  and  the  lines  drawn 
with  it  will  not  become  blurred  or  defaced  when  exposed  to 
moisture. 

Drawing  ink  of  practically  any  color  can  be  obtained,  but 
only  black  ink  should  be  used  in  making  working  drawings 
unless  there  is  some  special  reason  for  using  inks  of  other  colors. 
Red  ink  is  used  occasionally  for  making  dimension  lines,  center 
lines,  etc.,  but  this  is  considered  bad  practice,  as  the  ink  becomes 
faded  with  age,  and  in  the  case  of  a  tracing  the  lines  will  not 
be  sufficiently  opaque  to  print  well. 

The  use  of  bottled  India  ink  is  almost  universal  in  modern 
drafting-room  practice.  Drawing  ink  gradually  thickens  due 
to  evaporation  and  the  bottle  should  therefore  be  kept  tightly 
closed  when  not  in  use.  When  the  drawing  ink  becomes  too 
thick  it  may  be  thinned  by  adding  a  few  drops  of  diluted 
ammonia  or  distilled  water. 

If  the  stopper  and  filler  are  left  out  of  the  bottle,  the  ink  will 
dry  upon  them,  and  the  solid  particles  of  dry  ink  will  form 
small  clots,  which  may  be  transferred  to  the  pen  and  obstruct 
the  free  flow  of  the  ink. 

19.  Ordinary  pens.     Four  styles  of  pens  are  found  in  drafting 
rooms:  (i)  the  ordinary  writing  pen  with  fine  point;  (2)  the  or- 


DRAWING  INSTRUMENTS  AND  MATERIALS  19 

dinary  writing  pen  with  stub  point;  (3)  the  ball-pointed  pen; 
and  (4)  the  crow-quill  pen.  The  style  of  pen  selected  is  largely 
determined  by  the  width  of  the  lines  to  be  made.  An  expert 
draftsman  can  use  the  ordinary  fine-pointed  writing  pen  for 
almost  all  classes  of  work,  but  the  beginner  will  find  it  easier 
to  make  relatively  heavy  lines  with  the  stub-pointed  or  the  ball- 
pointed  pen. 

The  ball-pointed  pen  is  designed  to  glide  smoothly  in  any 
direction  and  at  the  same  time  make  a  line  of  uniform  width. 
It  has  little  tendency  to  catch  in  the  surface  and  splash  the  ink, 
and  therefore  permits  of  greater  freedom  in  any  direction  and 
order  of  strokes  when  lettering  or  making  free-hand  lines. 

The  crow-quill  pen  is  not  satisfactory  for  ordinary  work, 
especially  for  tracing,  as  the  tendency  is  to  make  the  lines  so  fine 
that  they  will  not  reproduce  in  printing. 

A  good  general  rule  to  follow  in  selecting  a  pen  is  that,  when 
perfectly  clean  and  carrying  a  reasonable  quantity  of  ink,  it  will 
make  a  line  of  the  desired  width  without  requiring  a  pressure 
great  enough  to  open  the  point. 

The  pen  selected  is  largely  a  matter  of  individual  preference, 
and  experience  will  soon  dictate  the  best  pen  for  the  different 
kinds  of  work.  Until  the  beginner  has  had  sufficient  experience 
to  make  an  intelligent  selection,  only  those  pens  called  for  in  the 
list  of  supplies  should  be  used.  (See  page  3,  §  2.) 

A  new  pen  often  gives  trouble  from  two  causes:  (i)  the  flow 
of  the  ink  may  not  be  free  and  uniform;  (2)  the  point  may  be 
stiff  and  catch  in  or  scratch  the  surface.  The  coating  of  oil 
which  has  been  put  on  the  pen  by  the  makers,  to  prevent  rust- 
ing, is  usually  the  cause  of  the  ink's  not  flowing  freely  on  a  new 
pen.  This  oil  can  be  removed  by  moistening  and  thoroughly 
wiping  the  pen  several  times,  or  by  rubbing  the  pen  with  finely 
pulverized  crayon  or  tracing-cloth  powder.  Dried  ink  on  the 
pen  point  will  also  give  trouble  and  for  this  reason  the  pen 
should  be  thoroughly  cleaned  each  time  before  dipping  for  a  new 
supply  of  ink. 

If  the  pen  is  stiff  it  may  be  improved  by  slightly  drawing  the 
temper.  This  is  done  by  holding  a  lighted  match  to  the  point, 
care  being  taken  not  to  overheat  it.1 


20  ELEMENTS   OF  DRAWING 

If  the  pen  point  catches  in  or  scratches  the  drawing  it  should 
be  rounded  by  a  few  light  strokes  on  an  oilstone  or  on  a  piece 
of  very  fine  emery  cloth. 

A  new  pen  always  requires  "  breaking  in  "  and  for  this  reason 
an  experienced  draftsman  will  take  as  much  care  in  preserving 
his  pen  as  if  it  were  one  of  his  more  costly  instruments.  Before 
putting  the  pen  away  always  clean  it  thoroughly  with  a  rag  free 
from  lint.  Common  writing  ink  should  not  be  used  on  a  pen 
intended  for  drawing,  as  it  corrodes  the  pen  and  renders  it  unfit 
for  further  use  with  drawing  ink. 

20.  Penholders.  The  penholder  should  hold  the  pen  securely 
and  firmly  and  should  be  of  such  a  size  and  shape  that  the  hand 
will  not  be  cramped.  Holders  of  small  diameter  are 
therefore  unsatisfactory.  The  cork-tipped  holder 
has  the  double  advantage  of  being  easy  on  the  fingers 
and  of  absorbing  moisture. 

21.  Ruling  Pens.  The  simplest,  and  probably  the 
best,  form  of  ruling  pen  consists  of  two  "blades" 
made  of  a  single  piece  of  metal  and  fastened  to  a 
handle,  as  shown  in  Fig.  16.  In  order  to  hold  a  fine 
edge  the  blades  must  be  made  of  the  best  tempered 
steel.  The  inner  blade  (into  which  the  screw  is 
tapped)  should  be  almost  straight.  The  outer  blade 
should  be  slightly  curved,  so  that,  when  the  points 
are  together,  there  exists  a  cavity  of  sufficient  capacity 
to  hold  enough  ink  to  do  a  reasonable  amount  of 
work  and  not  evaporate  too  rapidly  as  it  would  if  the 
film  of  ink  were  very  thin.  The  "nibs"  must  be 
even  in  length  and  terminate  in  a  slightly  rounded 

dinary  Ruling  point;  they  must  have  a  moderately  sharp  edge,  and 
must  be  broad  enough  not  to  wear  away  too  rapidly. 

The  handle  should  not  be  made  of  a  material  which  breaks  easily. 
The  adjusting  screws  of   all   instruments   should  have   an 

occasional  application  of  light  oil  to  prevent  rusting. 

To  adjust  the  pen,  hold  it  toward  the  light,  or  over  a  piece  of 

white  paper,  so  that  the  space  between  the  nibs  can  be  seen;  then 


DRAWING  INSTRUMENTS  AND   MATERIALS 


21 


Fig.  17.  — Charging  Ruling  Pen  with 
Ink. 


turn  the  thumb-screw  until  this  distance  is  the  width  of  the  line 

to  be  drawn.     To  fill  the  pen  (see  Fig.  17),  use  the  filler  that  is 

attached  to  the  stopper  of  the 

ink  bottle,  and  let  the  ink  flow 

between  the  nibs  until  it  is  nearly 

one-quarter  of  an  inch  from  the 

points. 
While   filling    the  pen  never 

hold  it  over  the  drawing  as  ink  is  often  dropped  during  the 

process.     After  the  pen  has  been  filled,  see  if  any  ink  has  gotten 

on  the  outside  of  the  nibs,  and  if  so,  wipe  them  off  with  a  clean 

rag  (seepage  33,  §30). 

To  use  the  pen  (see  Fig.  18),  hold  it  with  the  thumb  and  the 

first  two  fingers,  so  that  the  thumb-screw  is  away  from  the  body, 

and  the  pen  perpendicular  to  the  surface 
of  the  drawing.  The  third  and  fourth 
fingers  should  rest  lightly  on  the  triangle 
or  T-square  blade,  to  steady  the  hand 
and  control  the  pressure  of  the  pen 
against  the  drawing.  This  pressure  and 
the  speed  at  which  the  pen  is  moved 
along  the  ruling  edge  must  not  vary, 

Qr  the  ^  ^  ^    ^  uniform   thrOUgh- 

out  its  length.  The  pen  may  be  inclined  slightly  in  the  direc- 
tion in  which  the  line  is  being  drawn,  so  that,  in  moving,  the 
point  is  pulled  after  the  body  of  the  pen;  but 
under  no  condition  should  it  be  inclined  in  the 
opposite  direction,  making  it  necessary  to  push 
the  point  in  advance  of  the  body  of  the  pen. 
Move  the  pen  from  left  to  right  in  drawing 
lines,  which  are  horizontal  or  nearly  so,  from 
bottom  to  top  in  drawing  lines  which  are  vertical 
or  nearly  so,  and  in  either  direction  (depend- 
ing upon  the  angle)  in  drawing  inclined  lines 
(see  Fig.  10).  Always  hold  the  pen  so  that  a  Fi*-  '9.- Direction  m 

°         v/  J  *  which  to  draw  Ruled 

line  of  the  least  width  is  drawn  for  a  given  set-     Lines. 

ting  of  the  nibs.     In  no  case  is  the  ruling  pen  to  be  used  in 

making  free-hand  lines  as  this  is  liable  to  injure  the  nibs. 


Fig.  18.  —  Using  the  Ruling  Pen. 


22  ELEMENTS  OF  DRAWING 

The  blades  of  all  pens  must  be  kept  absolutely  clean,  both 
inside  and  out,  if  good  results  are  to  be  obtained.  More  unsatis- 
factory work  results  from  the  neglect  of  this  precaution  than 
from  any  other.  No  pen  can  be  expected  to  make  a  good  line 
when  the  blades  are  incrusted  with  dried  ink.  Ink  corrodes  the 
metal  points,  as  shown  by  the  magnified  view  in  Fig.  20,  and  the 

pen  is  finally  rendered  unfit  for  use. 

As  soon  as  the  ink  in  the  pen  begins  to  thicken,  pass 

a  str*P  °^  PaPer  or  c^ot^  between  the  blades,  and  refill 

the  pen;  but  never  refill  without  first  cleaning  the  inner 

surface  of  the  blades. 
Fig.  20.  —     To  clean  the  inner  surface  of  the  blades,  fold  a  piece 

Ruling  Pen      -  ,  ,  A  ,  ,     '  .,       ,  .    , 

Blade  cor-  of  unglazed  paper,   or  the  rag  penwiper,   until   thick 


°  spring  the  nibs  slightly  when  passed  between 
them.  Draw  the  paper  or  cloth  between  the  blades, 
from  the  screw  to  the  tip,  several  times,  or  until  it  shows  no 
ink,  even  after  being  moistened.  (See  Fig.  75,  page  no.) 
Besides  frequently  cleaning  the  pen  while  in  use,  the  blades 
should  be  opened  wide  and  given  a  thorough  cleaning  with  the 
instrument  wiper  before  it  is  put  away. 

The  points  of  the  pen  will  wear  dull  after  it  has  been  used  for 
some  time,  and  in  order  to  again  make  a  clear-cut  line  they 
must  be  resharpened. 

To  sharpen  the  ruling  pen,  first  clean  thoroughly  and  then 
close  the  blades  until  they  nearly  touch.  This  can  be  judged  by 
properly  holding  the  pen  to  the  light  or  over  a  piece  of  white 
paper.  Next,  keeping  the  pen  per- 
pendicular to  the  surface  of  a  flat, 
close-grained  oilstone,  move  back 
and  forth  until  the  nibs  are  "  square  " 
and  of  equal  length.  The  nibs  are 
then  rounded  to  a  radius  of  one 
thirty-second  of  an  inch  by  ruling  a 
line  on  the  oilstone  and  continually 

Fig.  21.  —  Rounding  the  Nibs  of 

changing  the  inclination  of  the  pen,  the  Pen. 

as  shown  in  Fig.  21.  This  process  dulls  the  edge  of  the  points 
and  they  must  then  be  sharpened  by  slightly  opening  the  blades 
and  rubbing  the  outer  surface  of  the  nibs  on  the  oilstone.  Care 


DRAWING  INSTRUMENTS  AND  MATERIALS 


must  be  taken  that  the  rounded  shape  of  the  end  is  not  altered; 
also  a  "  wire  edge  "  must  not  be  produced,  as  this  will  cut  the 
surface  of  the  paper  or  tracing  cloth. 

To  test  the  condition  of  the  pen,  clean  it  thoroughly  and  draw 
a  light  and  heavy  inked  line ;  if 
both  are  not  clear-cut  and  even, 
the  pen  requires  attention. 


JOINT- 


SOCKET  JOI 


22.  Compasses.  The  compass 
is  used  in  drawing  circles  and 
arcs  of  circles.  A  complete  com- 
pass outfit  (see  Fig.  2  2)  consists  of 
five  parts:  (i)  the  "headpiece"; 
(2)  the  "needle  point";  (3)  the 
"pencil  leg";  (4)  the  "pen  leg"; 
(5)  the  "extension  bar." 

The  instrument  may  be  made 
of  iron,  brass,  steel,  aluminum, 
or  German  silver,  the  best  being 
made  of  rolled  (not  cast)  German 
silver.  It  is  difficult  to  deter- 
mine the  quality  of  German  sil- 
ver by  inspection,  but  the  cast 
material  can  usually  be  detected 
by  its  high  glossy  finish. 

The  de- 
sign of  the 
compass 
should  be 

such  that  the  "head"  and  "knee  joints" 
a  allow  free  movement  of  the  parts  and  at 
the  same  time  give  proper  rigidity.  They 
should  be  so  designed  as  to  exclude  dirt 
and  moisture  and  should  fit  accurately. 

Fig.  23.-Head- Joint  Design.   The    SQcket    joints    should    fit    the    shank 

accurately,  hold  the  leg  in  proper  alignment,  and  have  a  clamping 
device  that  will  hold  the  interchangeable  parts  rigid.  Fig.  23 
shows  the  details  of  a  good  design  for  the  head  joint. 


Fig.  22. —  Compass  Outfit  Complete. 


ELEMENTS  OF  DRAWING 


TONGUE  SLfT 

(a)  Superior  design. 


The  legs  are  alike  at  this  joint,  and  two  pivoted  screws  are 
inserted  in  the  yoke  of  the  handle  to  hold  the  legs  in  position; 
small  set  screws  prevent  the  pivoted  screws  from  turning  in  the 
yoke.  All  contact  surfaces  are  made  circular,  which  insures  a 
close  fit  for  all  positions  of  the  legs,  and  thus  excludes  dirt  and 
moisture. 

Several  forms  of  socket  joints  are  shown  in  Fig.  24,  the 
design  as  shown  in  Fig.  24 (a)  being  the  best.  The  hole  is  made 

circular  and  slightly  tapered.  The  socket 
is  split,  and  the  clamping  screw  is  lo- 
cated on  the  side. 

The  handle  of  the  compass  is  some- 
times designed  so  that  no  matter  in 
what  position  the  upper  portion  of  the 
legs  are  set,  it  always  keeps  a  central 
position  relative  to  them,  and  conse- 
quently is  approximately  perpendicular 
to  the  surface  of  the  drawing  when  the 
instrument  is  being  used.  This  is  an 
advantage  unless  the  device  is  so  deli- 
cately constructed  that  the  wear  and  tear  arising  from  ordinary 
use  soon  render  the  entire  instrument  valueless. 

The  needle  point  consists  of  a  finely  tempered  steel  wire  which 
fits  into  a  cylindrical  socket  in  the  lower  end  of  the  attached  leg. 
It  should  fit  the  socket  with  a  snug,  sliding  fit,  and  be  clamped 
with  a  thumbscrew.  The  lower  end  of  the  needle  point  (which 
enters  the  drawing)  has  a  shoulder  to  support  the  weight  and 
pressure  on  the  instrument  when  in  use  and  thus  prevents  a 
hole  being  bored  in  the  drawing. 

Besides  the  knee  joint  and  the  shank  of  the  pencil  leg,  the  small, 
cylindrical,  split  socket  that  receives  the  lead,  and  the  clamping 
device  that  holds  the  lead  should  be  examined.  The  socket 
should  be  drilled  accurately  and  of  the  proper  size  to  receive 
the  lead  of  an  ordinary  drawing  pencil.  The  clamping  device 
should  exert  a  uniform  pressure  along  the  entire  length  of  the 
socket  and  hold  the  lead  secure  and  firm. 

The  remarks  on  the  design  and  care  of  the  ruling  pen  (see 
page  20,  §  21)  apply  generally  to  the  pen  leg  of  the  compass. 


(b)  Inferior  designs. 
Fig.  24.  —  Socket-joint  Designs. 


DRAWING   INSTRUMENTS   AND   MATERIALS 


The  extension  bar  is  used  to  increase  the  range  of  the  com- 
pass, by  making  it  possible  to  draw  circles  of  a  larger  diameter 
than  can  be  drawn  with  the  compass  proper.  Its  design  is 
determined  by  the  design  of  the  socket  joint  of  the  compass. 

The  joints  of  instruments  should  have  an  occasional  applica- 
tion of  light  oil  to  prevent  rusting  and  insure  easy  working. 

To  prepare  the  compass  for  use,  insert  the  pen  leg  in  the  socket 
as  far  as  it  will  go,  and  then  clamp  it  securely  in  position.  Ad- 
just the  needle  point  so  that  the  point  of  the  pen  and  the  shoulder 
of  the  needle  are  even  when  the  compass  is  completely  closed. 
The  needle  point  is  now  adjusted  for  either  pen  or  pencil  and 
should  not  be  changed.  As  the  lead  in  the  pencil  wears  away, 
making  readjustment  necessary,  the  position  of  the  lead  should 
be  changed  and  not  the  needle  point.  The  lead  is  usually 
sharpened  to  a  chisel  edge  (see  page  15,  §  14)  which  must  be 
tangent  to  the  arc  it  draws.  It  is  adjusted  by  clamping  the  pencil 
leg  in  the  instrument  and  adjust- 
ing the  lead  until  the  end  is  even 
with  the  needle  point  when  the 
compass  is  completely  closed. 

To  draw  a  circle,  bend  both 
legs  at  the  knee  joints  an  equal 
amount,  and  enough  to  bring  the 
marking  point  and  the  needle 
point  each  perpendicular  to  the 

Fig.  25.  —  Using  the  Compass. 

surface  of  the   drawing  when 

the  instrument  is  being  used.  This  adjustment  (see  Fig.  25) 

places  the  needle  point  in 
such  a  position  that  it  will 
make  the  smallest  hole  pos- 
sible in  the  drawing  and 
|  insures  both  nibs  of  the  pen 
bearing  evenly  on  the  paper. 
The  proper  opening  be- 
tween the  points  (the  ra- 
dius) may  be  taken  from  the 

Fig.  26. -Setting  or  Reading  the  Instrument.         measuring   SCale,  as   shown 

in  Fig.  26,  or  the  extremities  of  the  radius  may  be  marked  from 


26 


ELEMENTS  OF  DRAWING 


the  scale  directly  on  the  drawing  in  their  proper  position  and  the 
compass  set  to  them,  the  latter  method  being  preferable  as  there 
is  less  chance  of  injury  to  the  scale  division  marks. 

To  use  the  compass  hold  the  handle  of  the  instrument  lightly 
between  the  thumb  and  the  first  and  second  fingers;  guide  the 
needle  point  to  the  center  of  the  circle  by  sliding  it  on  a  finger 
of  the  left  hand;  hold  the  compass  so  that  both  the  marking 
and  the  needle  points  are  perpendicular  to  the  surface  of  the 
drawing  and  remain  so  while  making  the  circle.  Place  the  needle 
point  at  the  center,  and  the  marking  point  at  the  bottom  of  the 
g  in  circle,  and  with  a  slight  pressure  against  the  drawing 
rotate  the  compass  right  handed,  that  is,  in  the  same 
direction  as  the  hands  of  a  clock  move  (never  the 
reverse)  by  rolling  the  handle  between  the  thumb 
and  first  finger. 

All  inked  arcs  and  circles  should  be  made  by  one 
continuous  revolution,  and  where  any  portion  of  a 
line  is  so  thin  or  ragged  as  to  require  retracing,  the 
entire  line  should  be  retraced. 

The  compass  should  be  manipulated  with  one 
hand,  unless  the  lengthening  bar  is  used,  then  the 
needle  point  should  be  steadied  with  one  hand,  and 
the  marking  point  rotated  with  the  other. 

23.   Dividers.    The  dividers  (see  Fig.  27)  are  used 
to  transfer  distances  from  one  point  to  another,  or 
to  divide  lines  or  circles  into  equal  parts,  but  they 
should  not  be  used  to  transfer  measurements  from 
the  scale  to  the  drawing  when  this  process  injures  the 
division  marks  on  the  scale.     See  page  25,  Fig.  26. 
Neither  should  the  dividers  be  used  where  it  is 
possible  to  lay  off  or  measure  distances  accurately 
Fig.  27.— or-  with  the  drawing  scale.     See  page  30,  Fig.  32. 
iary  Dividers.      jn  Design  £ne  dividers  are  similar  to  the  compass, 
and  the  main  points  considered  with  reference  to  the  compass 
apply  to  the  dividers  (see  page  23 ,  §  2  2) .     The  legs  of  the  dividers 
must  be  of  the  same  length,  and  the  steel  points  should  be  conical 
and  sharp.     One  of  the  legs  should  be  provided  with  a  hair- 


DRAWING  INSTRUMENTS  AND  MATERIALS 


POINTS 

Fig.  28.  —  Ordinary  Bow 
Dividers. 


spring,    controlled    by   a    thumbscrew,    to    facilitate    delicate 
adjustment. 

To  divide,  or  step  off,  a  line  or  circle,  manipulate  the  dividers 
with  one  hand,  and,  with  first  one  divider  point  and  then  the 
other  as  a  center,  rotate  the  dividers  alter- 
nately to  the  right,  then  to  the  left  as  if 
describing  a  series  of  semicircles. 

To  insure  accuracy  and  neatness,  the 
dividers  should  never  be  lifted  entirely  off 
the  paper  while  being  used,  and  the  points 
should  merely  rest  on  the  drawing  and  not 
puncture  it. 

24.  Bow  Dividers.  The  bow  dividers 
(see  Fig.  28)  are  used  in  the  same  manner 
and  for  the  same  purpose  as  the  large 
dividers  (see  page  26,  §  23). 

The  bow  dividers  when  once  set  main- 
tain a  fixed  distance  or  radius  and  there- 
fore in  "stepping  off"  distances  they  should  be  used  in  preference 

to  the  large  dividers. 

The  points  to  be  observed  in  select- 
ing, using,  and  caring  for  the  other  bow 
instruments  apply  largely  to  the  bow 
dividers  (see  §  25,  this  page). 

25.  Bow  Pencils.  This  instrument 
is  practically  a  pencil  compass  of  small 
radius.  In  making  small  arcs  or  circles 
it  has  the  advantage  of  being  easier  to 
handle  than  the  large  compass,  also  in 
drawing  several  arcs  or  circles  of  the 
same  diameter  (as  for  example  in  repre- 
senting bolt  holes,  boiler  tubes,  fillets, 
corners,  etc.)  there  is  less  liability  that 
the  distance  between  the  points  (that  is  the  radius)  will  be 
changed  in  the  handling  of  the  instrument.  The  ordinary  form 
of  Bow  Pencil  is  shown  in  Fig.  2Q(a). 


LEAD 

(a)  Ordinary  Design. 
Fig.  29.  —  Bow  Pencils. 


28  ELEMENTS  OF  DRAWING 

The  legs  of  the  bow  pencil  should  be  made  of  one  continuous 
piece  of  steel,  finished  and  tempered ;  the  handle  should  be  made 
of  metal,  as  ivory  and  bone  handles  break  too  easily;  the  needle 
point  should  be  made  of  tempered  steel  and  should  have  a  well- 
formed  shoulder  (see  page  24,  §  22).  The  spring  should  be 
strong  and  stiff;  the  threaded  parts  cut  smooth  and  true,  and 
the  adjusting  screw  capable  of  bringing  the  needle  and  lead 
points  together. 

Another  design  of  spring  instruments  [see  Fig.  29  (b)]  has  a 
central  thumbscrew  and  a  right  and  left  thread  working  in  swivel 
sockets.  The  advantage  claimed  for  this  design 
is  that  the  instrument  can  be  set  in  one  half  the 
time  required  to  set  the  instrument  shown  in 
Fig.  2  9  (a) .  The  disadvantages  are  that  the  radius 
is  much  more  liable  to  change  in  handling,  and 
the  swivel  sockets  are  necessarily  delicate,  easily 
injured  and  wear  rapidly. 

The  lead  used  is  the  same  as  for  the  compass, 
and  it  is  sharpened  and  adjusted  in  the  same 
manner  (see  page  25,  §  22),  except  for  extremely 
small  circles,  when  the  lead  should  be  sharpened 
to  a  conical  point  (see  page  15,  §  14). 

To  set  the  bow  pencil  shown  in  Fig.  2g(a),  first 
(b)  instrument  with  make  an  approximate  adjustment  by  compress- 

Cemg'f^-^T'  ing  the  sPrinS  with  the  finSers  and  settinS  the 
Pencils.          thumbscrew  (this  will  minimize  the  wear  on  the 

adjusting  screw  thread);  then  make  the  final  adjustment  with 
the  thumbscrew.  The  bow  pencil  is  manipulated  in  the  same 
manner  as  the  compass  (see  page  25,  §  22). 

An  important  test  of  the  bow  pencil  is  to  remove  the  lead  and 
clamp  a  needle  point  in  its  place  (the  instrument  now  has  two 
needle  points);  then  close  the  instrument,  and  if  the  two  points 
meet  exactly,  the  sockets  for  the  lead  and  for  the  needle  point 
are  accurately  drilled  and  the  instrument  should  do  satisfactory 
work;  otherwise  work  is  liable  to  be  inaccurate. 

26.  Bow  Pens.  The  bow  pen  (see  Fig.  30)  is  used  to  ink  the 
circles  and  arcs  that  have  been  penciled  with  the  bow  pencil. 


DRAWING  INSTRUMENTS  AND  MATERIALS  29 

Its  advantages  over  the  compass  are  the  same  as  those  of  the  bow 
pencil  (see  page  27,  §  25).  The  general  requirements  of  the  bow 
pen  are  about  the  same  as  those  for  the  bow  pencil,  and  the 
remarks  on  the  care,  use,  and  sharpening  of  the  ruling  pen  apply 
to  the  bow  pen  (see  page  20,  §  21). 

The  edge  of  the  pen  should  be  tangent  to  the  circle,  being 
drawn  so  that  a  clear  cut  line  of  uniform  width  is  made, 
and  when  the  instrument  is  closed  the 
needle  point  should  touch  the  pen  at 
the  middle  of  the  blade  end. 

27.  Scales.  The  purpose  of  the  scale 
is  to  make  measurements  on  the  draw- 
ing, and  it  should  never  be  used  as  a 
straightedge  for  drawing  lines. 

There  are  two  drawing  scales  in  gen- 
eral use:  the  civil  engineer's,  or,  as  it  is 
usually  called,  the  "engineer's  scale/' 
and  the  mechanical  engineer's,  or  the 
"architect's  scale."  These  scales  differ 
in  the  way  their  inch  spaces  are  sub- 
divided. 

The  engineer's  scale  divides  the  inch  into  such  decimal  parts 
as  tenths,  twentieths,  thirtieths,  etc.,  and  is  used  in  such  work  as 
map  drawing,  plotting  stress  diagrams,  measuring  indicator  cards, 
and  in  certain  government  work. 

The  architect's  scale  is  graduated  into  duodecimals  (twelfths), 
to  correspond  to  the  ordinary  foot  rule  used  by  the  workman  in 
the  shop;  the  duodecimal  is  divided  into  halves,  quarters, 
eighths,  sixteenths,  thirty-seconds,  etc.,  and  the  scale  is  used  for 
making  all  drawings  of  objects  which  are  to  be  dimensioned  in 
the  ordinary  foot-rule  denominations.  This  includes  practically 
all  mechanical  drawings. 

The  best  scales  are  made  of  boxwood  and  have  beveled  edges 
lined  with  a  white  material  resembling  ivory.  The  division 
marks  and  figures  are  printed  in  black  on  this  white  background, 
and  are  very  distinct  and  easy  to  read.  There  are  two  forms  of 
scale  in  general  use:  the  flat  scale  with  beveled  edges,  and  the 


NEEDLE  POnVT 

Fig.  30.—  Ordinary  Bow  Pen. 


ELEMENTS  OF  DRAWING 


scale  of  triangular  cross  section.  The  latter  form  is  shown  in 
Fig.  31  and  has  the  advantage  of  combining  eleven  distinct 
scale  divisions  on  a  single  instrument. 

Scales  are  made  of  different  lengths,  but,  in  order  to  be  provided 
with  a  full-size  one-foot  rule,  the  twelve-inch  length  (not  counting 
the  small  spaces  at  each  end,  which  are  to  protect  the  end  grad- 
uations) is  recommended.  The  numerals  printed  on  these  end 


Fig.  31.  —  Ordinary  Triangular  Scale. 

spaces  indicate  the  size  of  the  scale  along  that  bevel;  thus  the 
number  ij  on  the  end  of  the  scale  (shown  in  Fig.  31)  denotes 
that  this  bevel  is  divided  into  spaces  one  and  one-half  inches 
long  and  is  used  to  make  drawings  in  which  a  length  of  i| 
inches  represents  i  foot  (12")  of  the  object  represented.  The 
first  inch  and  one-half  length  is  subdivided  into  twelve  equal 
parts,  and  each  of  these  divisions  represents  one-twelfth  of  a 
foot,  or  one  inch.  The  row  of  figures  o,  i,  2,  3,  etc.,  indicates 
the  divisions  that  represent  i  ft.,  2  ft.,  3  ft.,  etc.  (measuring  from 
the  o  mark),  on  a  scale  on  which  ij  inches  equal  one  foot.  On 
some  scales  the  length  taken  to  represent  one  foot  is  so  small 
that  inches  cannot  be  indicated.  Thus,  on  the  -/y  scale  the 
unit  (sV)  is  divided  into  four  parts,  so  that  each  of  these  sub- 
divisions represents  one-fourth  of  one  foot,  or  3  inches,  and  the 
eye  is  relied  upon  to  divide  this  space,  representing  3  inches, 

into  still  smaller  divisions. 

To  use  the  scale  in  mark- 
ing off  a  distance,  apply  it  to 
the  drawing  so  that  it  lies  flat 
on  the  surface  (see  Fig.  32) 
and  in  a  position  to  receive 

Fig.  32.  -  Using  the  Scale.  ^  best  light  possible  on  the 

division  marks  and  numerals;  then  mark  the  points,  defining 
the  distance,  with  a  6H  pencil  sharpened  to  a  fine  cone  point 
(seepage  15,  §  14).  The  scale  is  applied  in  a  similar  manner 
in  measuring  distances  on  a  drawing. 


DRAWING  INSTRUMENTS  AND  MATERIALS  31 

Care  must  be  taken  not  to  injure  the  sharpness  of  the  edge  of 
the  scale  or  the  division  marks  and  numerals. 

Measurements  should  ordinarily  be  taken  directly  from  the 
scale  and  not  transferred  from  the  scale  to  the  drawing  by  means 
of  a  pair  of  dividers,  especially  if  by  so  doing  the  scale  divisions 
become  defaced. 

Where  it  is  necessary  to  set  an  instrument  to  a  measurement, 
as  for  example  the  radius  of  an  arc,  the  best  method  is  to  lay 
the  scale  on  the  paper  and  adjust  the  instrument  along  its  edge, 
so  as  to  avoid  scratching  or  defacing  the  graduations  on  the 
scale  with  the  points  of  the  instrument.  Where  this  method  is 
not  accurate,  set  the  instrument  as  shown  in  Fig.  26,  page  25. 

To  mark  off  a  number  of  consecutive  measurements,  such  as 
2",  5",  i",  and  |",  along  any  straight  line,  keep  the  scale  station- 
ary, and,  beginning  at  zero,  mark  off  in  succession  the  distances  2", 
2*  +  5"  =  7",  2"  +  5"  +  i"  =  8",  and  2"  +  5"  +  i"  +  y  =  8J". 
By  this  method  the  length  of  the  line  is  equal  to  the  sum  of  the 
lengths  of  all  its  parts,  and  the  accumulation  of  error  which  is 
likely  to  result  from  moving  the  scale  along  the  line  and  mak- 
ing each  measurement  an  independent  operation  is  avoided. 

To  test  the  accuracy  of  a  scale,  mark  off  the  divisions  to' be 
tested  along  a  straight  line.  Reverse  the  scale,  and  if  the  sub- 
divisions do  not  coincide,  the  scale  is  inaccurate. 

28.  Protractors.  The  protractor  is  an  instrument  for  measur- 
ing or  laying  off  angles.  It  may  be  made  of  paper,  celluloid, 
brass,  German  silver,  or  steel. 
The  two  latter  materials  are  the 
most  satisfactory. 

Fig.  33  illustrates  the  style  of 
protractor  in  most  general  use, 
but  more  elaborate  designs  may 
be  had. 

TO    USe    this  protractor,    place  Fig.  33- -Ordinary  Protractor. 

it  so  that  the  two  zero  marks  coincide  with  the  given  line 
(produced  if  necessary),  and  the  center  (C)  coincides  with  the 
vertex  of  the  desired  angle.  The  protractor  is  now  in  correct 
position  for  reading.  If  a  line  is  to  be  drawn,  making  a  desired 


ELEMENTS   OF  DRAWING 


angle  with  the  given  line,  use  a  cone-pointed  pencil  (see  page  15, 
§  14)  and  mark  a  very  fine  point  on  the  drawing  just  at  the 
outer  edge  of  the  protractor  and  opposite  the  desired  angle- 
division  on  the  scale,  and  a  line  drawn  through  this  point  and 
the  point  C  will  make  the  desired  angle  with  the  original  line. 


29.  Machinist's  Calipers,  Dividers,  and  Steel  Rule.  To  make 
a  drawing  of  any  existing  object,  for  example  a  machine,  all  of 
the  principal  dimensions  must  be  obtained.  These  measure- 
ments should  always  be  made  with  a  two-foot  rule  or  a  ma- 
chinist's steel  rule  and  not  with  the  draftsman's  scale.  Apply 
the  measuring  rule  as  close  to  the  part  to  be  measured  as  possible. 

By  use  of  the  dividers  and  the 
calipers,  measurements  otherwise 
inaccessible  can  often  be  made. 
The  best  calipers  and  dividers 
are  made  of  finely  tempered  steel 
and  are  provided  with  a  spring 
nut  (see  Figs.  34,  35,  and  38) 
which  admits  of  rapid  adjust- 
ment. 

The  outside  calipers  (see  Fig. 
34)  are  used  to  determine  the 
diameters  of  cylinders,  the  thick- 
ness of  flat  parts,  etc.,  and  the  inside  calipers  (see  Fig.  35)  are 
used  to  determine  the  diameters  of  holes  or  other  inside  dimen- 
sions inaccessible  to  the  scale. 

To  insure  accurate  results,  the  calipers 
must  always  be  held  against  the  piece 
being  measured  in  such  a  manner  that  the 
dimension  desired  will  be  a  line  which  is 
the  shortest  distance  between  the  points  of 
the  calipers.  For  example,  to  find  the 
diameter  of  a  cylinder,  the  calipers  should 
be  held  in  a  plane  perpendicular  to  the  axis 
of  the  cylinder,  and  then  adjusted  until 
its  points  will  just  pass  freely  over  the  cylinder.  To  read  the 
distance  between  the  points  of  outside  calipers,  place  one  of  the 


Fig.  34-  —  Ordinary 
Outside  Calipers. 


ig'  35-  —  Ordinary 
Inside  Calipers. 


Fig.  36.  —  Reading  the 
Outside  Calipers. 


DRAWING  INSTRUMENTS  AND   MATERIALS 


33 


points  against  the  end  of  the  rule  and  the  other  against  the  face, 
as  shown  in  Fig.  36.  To  read  the  distance  between  the  points  of 
the  inside  calipers,  place  the  end  of  the  rule  and  one  point  of 
the  calipers  against  a  flat  surface,  as 
shown  in  Fig.  37. 

The  dividers  (see  Fig.  38)  can  often 
be  used  to  determine  dimensions  with 
a  greater  degree  of  ac- 
curacy than  is  possible 
with  the  rule.  To  make 
a  measurement  with  the 
dividers,  their  points 

are  adjusted  to  fit   the    Fig<  37._  Reading  the  Inside 
limits   of    the    distance  calipers, 

to  be  measured,  and  the  points  of  the  dividers 
are  then  applied  to  the  steel  rule,  as  shown  in 
Fig.  26,  page  25. 

Measurements  that  must  be  made  extremely 
Fig.  38.-  ordinary  accurate  cannot  always  be  obtained  satisfactorily 
Machinist's  Dividers.  with  either  the  measuring  instruments  or  by 
the  methods  of  making  measurements  as  described  above. 

To  measure  accurately  in  hundred ths,  thousandths,  etc.,  of 
an  inch,  special  instruments  are  used,  the  most  common  of 
which  is  the  Micrometer;  a  discussion  of  this  instrument,  how- 
ever, is  beyond  the  scope  of  this  work. 

30.  Blotter,  Penwiper  and  Instrument  Rag.  An  ordinary 
blotter  is  often  useful  to  the  beginner  to  remove  the  top  of  a 
blot  globule,  but  should  never  be  used  to  blot  the  lines  of  the 
drawing.  This  dims  the  lines  and  tends  to  smear  the  work. 

A  small  linen  rag  should  be  kept  handy  for  cleaning  the  ink 
off  the  pens. 

The  instrument  rag  should  be  soft  and  free  from  lint.  It  is 
used  in  keeping  instruments  clean,  but  especially  in  removing 
dust  and  dirt  from  the  triangles  and  from  the  T-square  blade. 
If  these  instruments  are  not  perfectly  clean,  they  quickly  soil 
the  drawing  in  sliding  over  the  surface.  This  rag  should  not  be 
used  to  clean  the  ink  off  the  pens. 


CHAPTER  II 
LETTERS,   NUMERALS,   AND   LETTERING 

31.  Introductory.     Good  lettering  and  dimensioning  on  work- 
ing drawings  is  of  prime  importance  and  cannot  be  too  strongly 
urged.     A  drawing  may  be  well  made  and  correct  in  all  its  de- 
tails, but  if  the  lettering  be  poorly  done,  the  general  appearance 
will  be  unsatisfactory  and  the  value  questionable.     In  most  draw- 
ings the  appearance  is  quite  important,  and  in  all  it  is  desirable 
to  secure  the  most  pleasing  effect  possible.     This  does  not  mean 
that  the  lettering  should  be  elaborate,  or  an  effort  made  to  secure 
artistic  effects.     There  is  no  demand  for  such  lettering  on  working 
drawings,  but  a  style  which  is  neat,  well-appearing,  easily  read 
and   easily  made  is  required.     The  inclined   Gothic  alphabet, 
being  free  from  unnecessary  ornamental  and  superfluous  features, 
fulfills  all  the  requirements  of  lettering  on  engineering  drawings 
and  has  been  very  generally  adopted  in  practice. 

The  ability  to  do  good  lettering  with  this  style  of  alphabet 
depends  only  upon  a  degree  of  manual  skill  that  any  beginner 
can  acquire  by  intelligent  practice  combined  with  careful  obser- 
vation of  the  characteristics  of  the  alphabet. 

32.  The  Study  of  Lettering.     Most  beginners  look  upon  free- 
hand lettering  as  a  difficult  but  purely  mechanical  process.     This 
is  a  serious  mistake,  and  as  a  result  progress  is  retarded  and  the 
work  is  uninteresting. 

The  letters  and  numerals  in  the  alphabets  have  been  evolved 
through  years  of  use,  and  unless  the  beginner  studies  their  form 
and  proportions  and  endeavors  to  reproduce  them,  he  cannot 
hope  to  acquire  the  art  of  lettering.  The  outline  and  character- 
istics of  each  letter  and  numeral  must  be  carefully  studied  and 
fixed  in  the  mind.  The  beginner  is  greatly  aided  in  learning 
the  characteristics  of  the  letters  of  the  alphabet  by  so  grouping 

34 


LETTERS,  NUMERALS,  AND  LETTERING  35 

them  that  comparisons  can  be  made  as  to  their  points  of  sim- 
ilarity and  difference;  for  example,  groups  could  be  made  up  as 
follows: 

(a)  Letters  composed  entirely  of  straight  lines. 

(b)  Letters  composed  wholly  or  partly  of  curved  lines. 

(c)  Letters  of  the  same  width. 

(d)  Letters  of  the  same  height. 

(e)  Letters  of  similar  outline. 

Thus,  /,  Z,,  E,  and  F  form  a  group  of  letters  all  of  which 
begin  with  a  line  of  "  standard  slope"  (i.e.,  a  line  which  has  the 
same  slope  as  the  alphabet)  and  have  parallel  branches.  The 
"  bar  "  in  both  the  E  and  F  is  exactly  midway  between  the  top 
and  bottom  of  the  letter,  and  its  length  is  the  same  as  its  dis- 
tance from  the  top  or  bottom;  it  is  more  than  one-half  but  less 
than  three-fourths  as  long  as  the  upper  width  of  the  letter.  The 
top  width  of  the  E  equals  that  of  the  F,  but  the  lower  width  of 
the  E  is  five  units  while  the  lower  width  of  the  L  is  only  four  and 
one-half  units.  The  fact  that  E  is  wider  at  the  bottom  than  at 
the  top  suggests  another  group,  composed  of  E,  B,  K,  Z,  and  X, 
all  of  which  are  wider  at  the  bottom  than  at  the  top.  The 
reason  for  making  these  letters  wider  at  the  bottom  is  to  give 
an  appearance  of  stability.  If  these  letters  are  made  the  same 
width  throughout,  they  appear  top-heavy.  The  /,  H,  N,  and  M 
have  parallel  sides  which  have  the  slope  of  the  alphabet  and 
would  not  appear  well  if  made  wider  at  the  bottom.  There  is  a 
difference  in  the  slope  of  similar  sides  of  V  and  W,  and  neither 
contains  a  line  of  standard  slope.  Other  groups  that  should 
be  studied  are  O,  Q,  C,  and  G;  P,  R,  and  B;  U  and  /;  a,  d,  q, 
and  so  on.  This  method  of  studying  the  alphabet  and  compar- 
ing letters  will  develop  a  fine  sense  of  proportion  and  will  also 
train  the  eye  to  see  form  properly,  both  of  which  are  essential 
not  only  in  lettering  but  also  in  sketching  and  drawing. 

Ultimately  the  draftsman  does  not  rely  upon  his  memory  for 
spaces,  widths,  heights,  and  proportions  of  the  letters,  but  this 
sense  of  proportion  enables  the  eye  to  judge  the  accuracy  of 
the  construction,  the  alignment  of  the  letters,  and  the  proper 
spacing  while  the  letters  are  being  formed,  and  lettering  free-hand 


36  ELEMENTS  OF  DRAWING 

is  then  no  more  difficult  or  tiresome  than  writing.  Progress  at 
the  start  will  depend  in  a  large  measure  upon  the  beginner's 
ability  to  criticize  his  own  work  and  his  willingness  to  correct 
all  errors  as  soon  as  they  are  detected. 

If  patience  and  thought  are  exercised  from  the  start  the  be- 
ginner will  soon  acquire  the  ability  to  do  good  lettering  and  it 
will  then  take  no  longer  to  make  well-formed  letters  than  poorly- 
made  ones. 

To  make  a  critical  study  of  lettering,  note  as  follows : 

(a)  Whether  the  tops  and  bottoms  of  the  letters  appear  to  be 
in  line. 

(b)  If  the  proper  spacing  has  been  maintained  between  letters, 
words,  sentences,  and  lines  of  lettering. 

(c)  If  each  letter  has  the  proper  slope. 

(d)  If  each  letter  has  the  proper  proportion  of  height  to  width. 

(e)  If  the  different  lines  composing  each  letter  are  the  proper 
relative  length  and  shape. 

It  will  be  observed  that  the  first  thing  to  notice  is  whether  the 
letters  appear  to  be  in  line.  In  lettering,  mathematical  measure- 
ments will  not  always  produce  satisfactory  results.  On  account 
of  the  sharp  angles  of  such  letters  as  A ,  V,  W,  and  the  curves  of 
O,  C,  Q,  G,  they  appear  shorter  than  such  letters  as  H,  N,  E, 
M,  when  made  exactly  the  same  height,  and  for  this  reason  it 
is  best  to  make  them  extend  very  slightly  beyond  the  guide  line 
in  order  to  have  them  appear  the  same  height.  Also  it  often 
happens  that  a  deviation  from  the  standard  width  of  letters  is 
an  advantage.  Thus,  an  L  followed  by  an  A  can  be  made  nar- 
rower than  if  it  were  followed  by  an  N  or  an  H,  or  than  if  it  were 
at  the  end  of  a  word. 

33.  Slope  of  Letters.  The  vertical  and  the  inclined  alphabets 
are  used  in  practice,  but  the  inclined  letters  are  usually  preferred, 
since  it  is  more  difficult  to  make  vertical  letters  appear  uniformly 
regular.  This  is  because  the  eye  naturally  compares  the  free- 
hand vertical  lines  of  the  letters  with  the  mechanically  made 
vertical  lines  of  the  drawing  and  consequently  any  slight  im- 
perfection is  noticeable.  Also,  to  be  correct  and  appear  well, 


LETTERS,  NUMERALS,  AND  LETTERING  37 

the  vertical  letters  must  always  be  exactly  vertical  or  at  right 
angles  with  the  bottom  guide  line,  while  with  the  inclined  letters 
the  exact  angle  of  inclination  is  not  of  great  importance  as  long 
as  uniformity  of  inclination  is  maintained,  and  the  draftsman 
may  give  his  letters  the  slope  that  is  easiest  for  him  to  maintain. 
While,  as  has  been  said,  inclined  lettering  is  usually  preferred, 
there  are  many  instances,  however,  where  vertical  lettering,  if 
well  done,  is  preferable. 

The  slope  to  be  used  in  this  work  is  2  to  i,  which  corresponds 
to  an  angle  of  about  63^°.  To  obtain  a  slope  of  two  to  one,  lay 
off  any  convenient  distance  along  a  straight  line  and  twice  this 
distance  on  a  second  straight  line  erected  at  the  right-hand 
end  of  and  at  a  right  angle  with  the  first  line.  A  third  line 
joining  the  extreme  outer  ends  of  these  two  lines  has  the 
slope  desired.  The  beginner  should  notice  that  the  lines  of  the 
inclined  alphabet  which  are  drawn  with  a  slope  of  two  to  one 
(that  is,  standard  slope  lines)  correspond  to  the  vertical  lines  of 
the  vertical  alphabet. 

34.  General  Description  of  Model  Letters.  The  illustrations 
in  §  38,  page  44,  and  §  41,  page  51,  show  the  correct  propor- 
tions of  the  letter,  and  the  written  matter  calls  attention  to 
certain  important  points  to  be  kept  in  mind  when  forming  the 
letter.  To  help  in  this  work,  "  guide  lines,"  "  center  lines," 
"  dimension  lines,"  and  "  direction  arrows  "  are  made  use  of. 

The  stem  of  a  letter  is  any  portion  of  the  outline  which  is 
straight  and  has  the  slope  of  the  alphabet,  this  term  being  most 
commonly  used  in  connection  with  the  description  of  the  small 
letters  of  the  alphabet. 

The  top  and  bottom  guide  lines  limit  the  height  of  the  letters 
and  are  an  aid  in  keeping  them  in  line.  The  side  guide  lines 
have  the  same  slant  as  the  alphabet.  They  limit  the  width  of 
the  letters,  and  aid  in  maintaining  the  proper  slope. 

Center  lines  are  used  on  letters  having  a  form  which  can 
be  divided  more  or  less  symmetrically  by  such  lines;  they  also 
determine  the  points  where  certain  letters  are  tangent  to  the 
guide  lines.  Center  lines  that  are  parallel  to  the  top  and  bot- 
tom guide  lines  are  called  horizontal  center  lines;  those  having 


38  ELEMENTS  OF  DRAWING 

the  same  slope  as  the  alphabet  are  called  standard  slope  center 
lines,  and  those  having  a  slope  other  than  that  of  the  alphabet 
are  called  sloping  center  lines.  A  letter  is  built  around  a  center 
line  in  somewhat  the  same  manner  as  a  sketch  would  be  built 
about  its  center  lines.  (See  page  137,  §  97.) 

Guide  lines  and  center  lines  for  lettering  should  be  drawn  con- 
tinuous or  unbroken  throughout  their  length,  but  very  light,  as  they 
are  erased  as  soon  as  the  lettering  is  completed. 

The  dimensions  shown  on  the  model  letters  will  enable  the 
beginner  to  study  the  relative  ratio  of  width  to  height  of  let- 
ters and  the  relative  proportions  of  the  different  lines  forming 
the  individual  letters.  (See  page  45,  §  38.) 

The  numbers  appearing  with  the  letter-dimension  lines  on 
the  model  indicate  the  units  of  space  between  the  arrowheads. 
This  unit  is  the  length  of  the  side  of  a  small  square  of  the  sec- 
tion paper,  and  on  the  paper  used  for  this  work  the  length  of 
a  side  is  \  inch,  so  that  3  would  indicate  the  length  of  three 
of  the  small  squares,  or  f  inch;  5  would  indicate  five  squares, 
or  f  inch,  etc.  (See  page  58,  §  44.) 

When  the  term  standard  slope  is  used  in  describing  the  model 
letters  and  numerals,  it  refers  to  a  line  of  the  letter  having  the 
same  slope  as  the  alphabet,  which  throughout  this  work  is  the 
slope  corresponding  to  2  to  i  or  approximately  to  63 J°. 

Direction  arrows  on  the  model  letters  point  in  the  direction  the 
pencil  should  move  in  making  each  stroke.  (See  page  64.) 

The  number  written  across  the  direction  arrow  indicates  the 
order  in  which  the  strokes  should  be  made.  (See  page  64.) 

This  system  of  strokes  should  be  closely  followed  by  the 
beginner,  as  it  points  the  way  to  easy  and  rapid  lettering. 
Later  on,  when  more  familiar  with  the  characteristics  of  the 
letters  and  when  greater  skill  has  been  gained  in  handling  the 
pencil  or  pen,  the  number  of  strokes  may  be  reduced  in  order  to 
acquire  speed,  but  the  first  stroke  should  be  the  one  which  determines 
the  spacing  between  the  letter  being  formed  and  the  preceding  letter, 
the  order  of  the  strokes  should  follow  the  easiest  method  of  secur- 
ing the  desired  outline,  and  the  general  direction  of  strokes  should 
be  either  down  (toward  the  body)  or  toward  the  right  when 
lettering  free-hand. 


LETTERS,  NUMERALS,  AND  LETTERING 


39 


35»  Spacing.  It  is  fully  as  important  to  place  letters  the 
proper  distance  from  one  another  as  it  is  to  form  them  correctly. 
Each  letter  in  a  word  may  be  perfectly  formed,  but  if  all  the 
letters  have  not  been  properly  spaced  the  lettering  will  not 
appear  uniform.  The  eye  judges  the  space  between  letters  as 
an  area  rather  than  a  linear  distance,  and  if  separated  by 
exactly  equal  distances,  the  areas  outlined  between  adjacent 
letters  will  not  be  uniform  in  different  combinations  of  straight 
and  curved  letters.  Thus,  a  combination  of  letters  with  stand- 
ard slope  sides  falling  adjacent,  as  MINE,  would  call  for  wide 
spacing  as  compared  with  such  a  combination  as  COG;  while 
the  adjacent  sides  of  the  letters  of  the  word  A  T  would  have  to 
" overhang"  so  that  the  spacing  may  appear  uniform.  Another 
extreme  combination  can  be  formed  of  half-open-side  letters,  as 
FTY.  If  it  were  possible  to  make  these  combinations  fall  in 
groups  as  illustrated,  it  would  not  be  difficult  to  state  rules 
for  spacing;  but  with  twenty-six  different  letters  a  great  many 
different  combinations  are  possible,  and  the  problem  of  spacing 
cannot  be  covered  by  a  single  rule.  Rules  that  will  prove  valuable 
to  the  beginner  are  given  below  but  the  appearance  of  the  fin- 
ished work,  in  so  far  as  spacing  is  concerned,  will  in  the  end 
depend  upon  the  judgment  exercised  in  maintaining  the  ap- 
pearance of  equal  areas  between  the  letters. 

The  distance  between  letters  is  measured  in  a  line  parallel  to 
the  top  or  bottom  guide-line  and  between  the  side-guide-lines 
which  fall  adjacent.  Based  on  this  idea  the  "  Key  to  Spacing  " 
(see  page  43)  has  been  compiled  and  the  distances  given  below 

4- 


\ 


8 


21-21 


/ 


', 


f 


4^- 


-/// 


A3- 


-// 


have  been  carefully  found  by  laying  out  on  a  large  scale  various 
side-line  combinations  (see  above  figure)  and  determining  a  spac- 


40  ELEMENTS  OF  DRAWING 

ing  that,  in  view  of  the  area  enclosed,  gives  the  best  spacing  for 
such  a  combination.  In  the  illustration  the  shaded  portion  rep- 
resents the  "  area  "  to  be  considered  in  determining  the  spacing 
which  is  shown  between  the  side-guide-lines. 

By  element  of  adjacency  is  meant  that  side-line  of  a  letter 
which  is  nearest  to  the  adjacent  letter  under  consideration. 

(A)  Spacing  for  various  line  combinations  in  Capital  Letters 
presented  in  three  different  forms  as  follows: 

(I)  Combinations  classified  by  space  units. 

(II)  Combinations  classified  by  side-line  grouping. 

(III)  Side-line  combinations  and  corresponding  spacing  shown 
by  chart. 

In  learning  to  space  method  (I)  should  be  the  guide  but  as  a 
further  aid  in  certain  combinations  method  (II)  or  (III)  can  be 
used  but  "  spacing  "  has  not  been  properly  grasped  until  the 
judgment  alone  is  relied  on  for  satisfactory  results. 

(I)    COMBINATIONS   CLASSIFIED   BY  SPACE  UNITS 

A  standard  slope  side  followed  by  a  standard  slope  side  re- 
quires three  and  one  half  spaces,  thus,  NS^N3^E. 

A  standard  slope  side  adjacent  to  a  curve  side  requires 
three  spaces,  thus,  CZH30SISC3E. 

A  combination  side  followed  by  a  standard  slope  or  a  curve 
side,  also  two  curve  sides  adjacent,  require  two  and  one  half 
spaces,  thus,  P^R^I^S^M^^S. 

A  standard  slope  side  followed  by  any  one  of  the  letters,  Z, 
V,  W,  A,  X,  also  any  one  of  the  letters  Z,  V,  K,  W,  A,  X, 
followed  by  V  or  W  or  by  a  standard  slope  side,  require  two 
spaces,  thus,  M-^A^K^E. 

A  standard  slope  side  followed  by  Y  or  T;  —  a  curve  or  combi- 
nation side  followed  by  any  one  of  the  letters  Z,  F,  W,  A ,  X;  — 
the  letters  K,  X,  or  Z  followed  by  a  curve  side;  —  any  one  of  the 
letters  L,  F,  F,  or  T  followed  by  a  standard  slope  side  require 
one  and  one  half  spaces,  thus,  F^L^E^W. 

All  other  combinations  require  one  space,  thus  T1O1Y1S,  except 
r,  Y  and  F  when  followed  by  A,  X  or  Z;  also  the  L  or  A  when 
followed  by  T  or  F,  which  require  zero  spacing,  thus  LQA0Y  or 
AQT,  etc. 


LETTERS,  NUMERALS,  AND  LETTERING  41 

(II)    COMBINATIONS    CLASSIFIED   BY   SIDE-LINE 
GROUPING 

Letters  with  a  standard  slope  side  [H,  I,  M,  N]  when  followed 

(1)  by  a  standard  slope  side  [B,  D,  E,  F,  H,  I,  K,  L,  M,  N, 
P,  R,  U]  require  3^  spaces. 

(2)  by  a  curved  side  [C,  O,  G,  Q,  S]  require  3  spaces. 

(3)  by  a  _L  or  a  45°  side  [V,  W-A,  X,  Z]  require  2  spaces. 

(4)  by  a  half -open  side  [T,  Y,  /]  require  i^  spaces. 

Letters  with  a  curved  side  [C,  0,  G,  Q-J,  U-B,  D]  when  followed 

(1)  by  a  standard  slope  side  [B,  D,  E,  F,  H,  I,  K,  L,  M,  N,  P, 
R,  U]  require  3  spaces, 

(2)  by  a  curved  side  [C,  O,  G,  Q,  S]  require  2\  spaces. 

(3)  by  a  J_  or  a  45°  side  [V,  W-A,  X,  Z]  require  i|  spaces. 

(4)  by  a  half -open  side  [T,  Y,  /]  require  i  space. 

Letters  with  a  combination  side  [R,  E,  P,  S]  when  followed 

(1)  by  a  standard  slope  side  [B,  D,  E,  F,  H,  I,  K,  L,  M,  N, 
P,  R,  U]  or  by  a  curved  side  [C,  0,  G,  Q,  S]  require  2\ 
spaces. 

(2)  by  a  J_  or  a  45°  side  [V,  W-A,  X,  Z]  require  i^  spaces. 

(3)  by  a  half-open  side  [T,  Y,  J]  require  i  space. 

Letters  with  a  -L  or  a  45°  or  a  full  open  side  [F,  W-A-K,  X,  Z] 
when  followed 

(1)  by  a  standard  slope  side  [B,  D,  E,  F,  H,  /,  K,  L,  M,  N,  P, 
R,  U]  require  2  spaces. 

(2)  by  a  _L  side  [V,  W]  require  2  spaces. 

(3)  by  a  curved  side  [C,  O,  G,  Q,  S]  require  ij  spaces. 

(4)  by  a  45°  side  [A ,  X,  Z]  require  i  space. 

(5)  by  a  half -open  side  [T,  Y-J]  require  i  space  or  o  space. 

.Letters  with  a  half-open  side  [L-F,  T,  Y]  when  followed 

(1)  by  a  standard  slope  side  [B,  D,  E,  F,  H,  I,  K,  L,  M,  N, 
P,  R,  U]  require  i|  spaces. 

(2)  by  a  _L  or  a  curved  side  [V,  W-C,  O,  G,  Q,  S]  require  i  space. 

(3)  by  a  45°  or  a  half -open  side  [A,  Xy  Z-T,  Y-J]  require  i  space 
or  o  space. 


42  ELEMENTS    OF  DRAWING 

(III)   SIDE-LINE  COMBINATIONS  AND  CORRESPOND- 
ING SPACING  SHOWN  BY   CHART 

The  chart  given  on  page  43  is  used  in  the  following  manner. 
Assume  as  an  example  that  the  letters  of  the  word  COLLEGE  are 
to  be  spaced.  First,  in  the  left-hand  column  locate  the  letter  C, 
then  move  horizontally  and  to  the  right  until  the  column  contain- 
ing the  capital  0  at  the  top  is  located,  and  it  is  seen  that  the  side- 
line classification  is  curved  side  followed  by  curved  side,  and,  reading 
directly  under  the  0  and  in  line  with  the  C,  the  spacing  is  i\ 
units.  Similarly  the  combination  of  the  letters  O  and  L  is  a 
curved  side  followed  by  standard  slope  line,  and  in  a  horizontal 
line  with  the  O  and  directly  under  the  L  the  chart  shows  the 
spacing  as  3  units.  Studying  out  all  the  combinations,  the  spac- 
ing is  as  follows:  C^O^Li^Li^^GsE. 

(B)  Spacing  for  Numerals.      The   "  standard "   spacing  for 
numerals  is  two  and  one  half  space  units  but  in  such  combina- 
tions as  involve  the  left  hand  side  of  the  j,  the  4  and  the  7  this 
distance  should  be  slightly  reduced  and  in  such  combinations  as 
involve  the  i  or  the  right  hand  side  of  the  4  (measured  from  the 
stem)  this  standard  spacing  is  slightly  increased. 

(C)  Spacing  for  Capital  Letters  in  combination  with  Small 
Letters  and  for  Small  Letters.    Small  letters  are  about  two  thirds 
the  height  of  capital  letters  and  numerals  of  the  same  alphabet 
and  hence  small  letters  require  a  spacing  of  about  two  thirds  that 
given  for  a  similar  side-line  combination  of  the  capital  letters. 

(D.)  Spacing  between  words  and  between  sentences.  Care 
must  be  taken  to  have  the  proper  space  between  words  and  a 
greater  space  between  sentences,  otherwise  the  lettering  is  not  so 
easily  read,  even  though  the  individual  letters  are  correctly 
formed  and  spaced. 

The  spacing  between  words  should  be  slightly  more  than 
twice  the  average  space  separating  letters. 

The  spacing  between  sentences  should  be  about  twice  that 
separating  words. 

Where  punctuation  marks  are  necessary  extra  space  is  allowed. 
The  punctuation  mark  is  placed  nearer  the  word  which  precedes 


LETTERS,  NUMERALS,  AND   LETTERING 


43 


\ 

^^ 

i 

^ 

. 

1 
1 
1 

. 

X 

d 

i 

- 

i 
"J     I 

v     ' 

^ 

1 

0    \ 

k  X 

|k 

•^> 

^ 

rv 

1 
I 

\ 

i 

i 
i 

& 

c 

i    | 

V     ' 
i     l 

^ 

Uj 

| 

l     l 

I 

1 

i 

1     l 

I 
| 

i 

\ 

N,^ 

\ 

I 

1 

N^ 

i 
1 

V 

l     i 

\!  ,  i 

\ 

1 

\  $ 

^ 

(V 

I 
| 

X 

^ 

— 

** 

v*^ 

-J 

^ 

k"^ 

8* 

' 

1 

i    i 

1 

Q 

| 

a 

M\ 

I 

^(\, 

i 

i    i 

1 

Q 

»\ 

X 

^^ 

i    i 

i. 

G 

UJ    \ 

1 

l 
l 

i    i 

1 

f\         ^" 

i    i 

| 

Uj  Uj 

^T      —  j^_ 

1 

i 

> 

?   ^i- 

^ 

i 

(V 

1 

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<\j 

— 

^ 

v^ 

^J 

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t^^ 

M 

s 

1 

i 

1   1 

1 

i 

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0)  (0 

^  ^ 

1 
| 

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1    1 

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s  ^ 

k  Uj 

S  § 

V. 

/v_ 

V. 

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Vj 

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Uj  Uj 

s  o 

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1     | 

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I 

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hk 

IV 

"-  n. 

x 

4, 

i 

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to 
» 

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(Y) 

^N 

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rv 

(\J 

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— 

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§ 

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1 

. 

1    1 

i 

THE  LEFT  HAND  >S 

STANDARD  SLOPE  SI 

DEFH/KLMF 

g 

C 

1 

l 

SPACING  -. 

1 

C 

1 

'§ 

£ 

8 

SPACING  

1 

I 

SPACING  

1 

SPAC/NG-. 

OMBINA  T/ON- 
SPACING  

S 

1 

SPACING  . 

OMBI  NATION- 
SPACING  

CD 

) 

L 

i 

*° 

• 

^ 

^ 

*° 

10 

^   § 

iy 

N 

p, 

IV 

\ 

(H 

v 

xj 

ITHE  RIGHT  HANL 
SIDES  OF  THE  LCTTE 

BELOW  ARE  fH£  EL 
A<TA/r.S  OFADJACEI\ 
C  CNSfDERED. 

STANDARD  SLOPE  S/i 

HIMN 

CURVE  SIDE  J> 

i 

c 

COWBi  'NATION  31  DE 

|  REPS 

APPF1GX  4-  5°  SIDE 

i 

\PERPENDICULAR  SID 

- 

FULL  OPEN  SIDE 

KXZ 

i 

^ 

0 
k 

k 

44  ELEMENTS  OF  DRAWING 

it  than  the  one  which  follows.  The  comma  and  the  semicolon 
each  require  a  space  between  the  mark  and  the  following  word 
equal  to  the  space  between  words. 

36.  Systematic  Method  of  Lettering.     Before  starting  the  out- 
line of  a  letter,  draw  very  lightly  all  guide  lines  and  center  lines 
that  will  be  an  aid  in  its  construction. 

When  forming  a  letter,  make  all  lines  very  light  at  first,  and, 
with  the  outline  correct,  retrace,  making  the  lines  of  medium 
weight.  • 

All  construction  lines  are  then  erased,  and  the  correct  outline, 
which  will  be  made  dim  by  the  erasing,  is  again  retraced  and 
made  clear  cut  and  of  the  desired  weight.  In  retracing,  the 
strokes  should  always  be  made  in  the  direction  and  order  indi- 
cated by  the  arrows  on  the  model  letters.  See  §  38,  this  page. 

For  full  instructions  as  to  how  to  make  free-hand  lines  see 
page  134,  §  95,  also  page  136,  §  96.  ^ 

37.  The  Size  and  the  Lettering  of  Letter  Sheets.     Exercises  in 
free-hand  lettering  will  be  done  on  small  sheets  of  standard  letter 
size  (8"  X  ioj"),  heavy  weight,  cross-section  paper  ruled  on  one 
side  (see  page  5,  §4),  and  punched  for  standard  #10  Manila 
cover. 

The  order  in  which  free-hand  lettering  sheets  are  executed  will 
be  indicated  by  capital  letters,  beginning  with  A  and  continuing 
as  far  as  necessary.  For  full  information  as  to  the  general  sys- 
tem to  be  followed,  see  Appendix,  page  175. 

SET   OF   FREE-HAND   LETTERING  EXERCISES. 

38.  Outline  and  Characteristics  of  Capital  (or  Upper-case) 
Letters  Composed  of  Straight  Lines  Only.     Over  half  of  the 
capital  letters  of  the  inclined  Gothic  alphabet  are  composed 
entirely  of  straight  lines,  and  several  of  these  straight-line  letters 
are  very  similar.     In  the  following  paragraphs  the  characteristics 
of  straight-line  capital  letters  are  pointed  out. 

In  order  to  fully  understand  the  subject  matter  of  this  para- 
graph, carefully  read  §  34,  page  37. 


LETTERS,  NUMERALS,  AND   LETTERING 


45 


1  ^ 

-3- 

—  *H 

)l 

l 

/ 

0 

^ 

Y 

i  X 

1 

y 

/ 

Capital  I.  i  stroke  of  standard  slope.  The 
width  of  the  letter  is  the  width  of  the  line  and 
should  not  differ  from  that  of  all  other  standard 
slope  lines.  Do  not  V 

dot  the  capital  /.     G.L- 


Capital  L.    2  strokes. 
If  i    is   standard    si 
#2  is  drawn  horizontal.     Note  that  $2  is 
shorter  than  the  corresponding  line  of  E. 


-41 


CO 


t/ 

M 

/ 

/ 

y 

I 

i 

j~ 

/ 

/•vm 

HOL 

-2- 

—  5- 

/ 

^ 

-s:— 

-< 

[7__ 

3. 

7 

G.L 

(See  this  page.) 
Capital  F.     3 

strokes.  #i  is  standard  slope;  $2  is  the 
same  as  #2  of  E  (see  this  page) ;  #3  starts 
from  the  middle  of  #i  and  is  drawn 
horizontal  and  should  never  be  drawn 
below  the  middle  of  the  letter  or  be  as 
long  as  #2. 


Capital  E.  4  strokes.  %i  is  standard 
slope;  #2  the  same  as  $2  of  F;  (see  this 
page) ;  #3  the  same  as  #3  of  F.  #4  is  par- 
allel to  #2  but  is  slightly  longer.  $2  is 
also  longer  than  the  corresponding  line 
of  the  L.  (See  this  page.)  Note  that 
#2  and  #4  are  each  shorter  than  the 
corresponding  lines  of  Z  (see  page  47). 

Capital  H. 


co 


$ 


A 


r — fr 

3  strokes. 


and  #2 

are  each  standard  slope.  Note  that 
these  two  parallel  lines  would  do  for 
the  N.  (See  page  46.)  #3  starts  at 
the  middle  of  #i,  is  drawn  horizontal 
and  should  never  be  drawn  below  the 

middle  of  the  letter.       L c! J 

2 


Capital  T.  2  strokes.  #i  is  drawn  horizontal. 
#2  is  standard  slope  and  is  drawn  from  a 
point  slightly  to  the  left  of  the  center  of  #i. 
Note  that  #i  is  longer  than  the  correspond- 
ing lines  of  E  (see  this  page),  F  (see  this 
page),  and  Z  (see  page  47). 


Stf 


ELEMENTS  OF  DRAWING 


Capital  N.  3  strokes,  fti  and  ft2  are 
each  standard  slope,  as  in  the  H.  (See 
page  45.)  Stroke  ft3  must  meet  fti  and 
#2  exactly  at  the  extremes  of  the  proper 

ends. 


II 


Capital  M. 

4  strokes. 

fti  and  ft2  are  each  standard  slope, 
and  are  drawn  a  distance  apart 
equal  to  the  height  of  the  letter. 
ft3  and  ft4  are  first  drawn  very  lightly, 
the  lower  segments  of  which  are  erased  in  the  finished  letter. 
The  angle  between  ft3  and  ft4  must  not  be  too  acute  or  the  letter 
-will  appear  to  be  compressed,  or  if  too  large  the  letter  will  appear 
"  widened."  The  M  is  not  the  same  as  the  W  inverted.  (See 

Page  47-)  , 

Capital  Y.     3  strokes,     fti  is  a  standard 

slope  line  drawn  through  the  center  of  the 

letter  but  slightly  less  than  the  lower  half  is 

used  in  the  completed  letter.    Strokes  ft2  and 

ft3  each  start  from  points  on  the  top  guide 

line  which  are  equidistant  from  the  inter- 
section of  fti  (extended)  and  the  top  guide 

line  and  meet  fti  slightly  below  the  center. 

Capital  V.  2  strokes.  Note  especially 
that  fti  is  vertical  and  ft2  makes  45°  with 
it;  also  the  letter  is  wider  at  the  top  than 
any  straight  line  letter  excepting  the  M 
(see  this  page)  and  the  W.  (See  page 
47.)  Also  fti  is  not 
parallel  to  ft2  of  the 

A  (see  page  47),  and  no  line  has 

the  standard  slope.    The  capital  and 

the  small  v  are  similar  (see  page  67). 
Capital  X.     2  strokes.     ft2  has  a 

slope  of  2  to  i  and  should  cross  fti    _J j* 

at  a  point  on  the  sloping  center  line  slightly^ 

above  the  center  of  the  letter,  thus  making 


—  «- 

-5- 

-p 

-»— 

'r 

*~ 

\\ 

/ 

/, 

f 

s 

/ 

/ 

4 

A 

'/ 

^ 

n 

._. 

~ 

/ 

/ 

0 

•* 

s| 

7 

1 

— 

] 

A\ 


^ 


LETTERS,   NUMERALS,    AND   LETTERING 


47 


the  letter  wider  at  the  bottom  than  at  the  top,  otherwise  it 
appears  top-heavy.  The  capital  and  the  small  x  are  similar. 
See  page  67. 

Capital  A.     3  strokes,     fti  makes  45° 
with  top  and  bottom  guide  lines.     ft2  is 
drawn  from  the  extreme  top  of  fti  to  the 
base  of  the  right  guide  line  and  is  not  a 
-  vertical  line,  thus  ft 2  is  not  parallel  to  fti  of 
the  V.     (See  page  46.)     ft3  is  horizontal 
and  one-third  the  distance  from  the  bot- 
tom to  the  top  of  the  letter,  and  thus  is 
always   below  the  center  of  the  letter. 
Note  that  no  lines  of  this  letter  have  the  standard  slope. 
Capital  K.    3  strokes,    fti  is  standard  'p — 5 

slope,  ft 2  is  drawn  to  meet  fti  at  a 
point  one- third  the  height  of  letter; 
i.e.,  below  center  of  letter.  ft3  is  drawn 
very  lightly,  the  upper  segment  of 
which  is  erased  in  the  finished  letter. 
Note  that  the  letter  has  a  greater  width 
at  the  bottom  than  at  the  top. 

Capital  Z.  3  strokes.  Draw  very 
lightly  two  sloping  side  guide  lines. 
fti  is  horizontal  and  starts  from  the 
left  guide  line.  ft3  is  parallel  to  fti, 
but  slightly  longer.  Note  that  fti  and 
ft3  are  longer  than  the  corresponding 
lines  of  the  E.  (See  .page  45.)  The 
"i  capital  and  the  small  z  are  similar.  See  page  67. 
Capital  W.  4  strokes.  No  stroke  ^j 
has  the  standard  slope,  fti  and  ft3 
each  incline  slightly  to  the  right 
and  are  parallel;  also  ft 2  and  ft4  are 
parallel.  Note  that  the  letter  W 
inverted  would  not  be  the  same 
as  the  M.  (See  page  46.)  The 
capital  and  the  small  w  are  similar. 
See  page  67. 


48  ELEMENTS  OF  DRAWING 

39.  Sheet  A.  The  purpose  of  this  sheet  is  to  teach  the  form 
and  characteristics  of  the  capital  letters  of  the  inclined  Gothic 
alphabet,  which  are  constructed  entirely  of  straight  lines,  also 
to  give  practice  in  making  these  letters. 

Before  starting  this  sheet  read  and  be  prepared  for  examina- 
tion on  the  following  paragraphs: 

The  Pencil  Pointer,  see  page  14,  §  13,  —  Lead  Pencil,  see  page 
14,  §14,  —  Erasers  and  Erasures,  see  page  16,  §15,  —  The 
Free-hand  Pencil  Line,  see  page  134,  §95,  —  Introductory,  see 
page  34,  §31,  —  the  Study  of  Lettering,  see  page  34,  §32,- 
The  Spacing  of  Letters,  Words  and  Sentences,  see  page  39,  §  35, 
and  for  information  on  the  general  system  to  be  followed  see 
page  175,  Appendix  A. 

Exercises  on  Sheet  A.  These  exercises  consist  of  capital 
letters  of  the  simplest  form.  Before  beginning  the  construction 
of  any  letter,  study  carefully  the  illustration  of  that  letter  in 
the  model  alphabet  (see  page  44,  §  38)  and  read  all  .descriptive 
matter  relating  to  it.  Also  see  §  37,  page  44. 

Do  not  use  a  straightedge  in  doing  any  part  of  a  free-hand 
exercise  as  this  will  seriously  impair  the  value  of  this  work. 
Lines  so  made  are  easily  detected  and  as  a  result  the  sheet  will 
not  be  accepted. 

Specific  Instructions  for  Executing  Sheet  A .  Tack  down  the 
sheet  (see  page  8,  §  9),  stamp  in  title  form  (see  page  138,  §  98) 
and  the  wording  in  the  title  form  is  next  to  be  neatly  written 
in  ink. 

The  title  of  sheet  A  is  CAPITAL  LETTERS. 

Proceed  with  the  letters  systematically,  and  complete  the  sheet 
as  shown  in  Fig.  39,  but  omit  arrows.  Practice  making  a  free- 
hand pencil  line  on  scrap  paper  before  starting  sheet  A .  This 
practice  can  best  be  accomplished  by  making  a  free-hand  copy 
of  some  simple  drawing,  such  as  Fig.  97  on  page  140,  continuing 
to  practice  until  a  "  clear  cut"  line  can  be  made  (see  page  78, 
§  54).  Also  the  beginner  should  at  this  time  learn  to  sharpen 
a  pencil  with  care  (see  page  15,  §  14)  and  to  use  an  eraser  to 
the  best  advantage  (see  page  16,  §  15). 


LETTERS,  NUMERALS,  AND  LETTERING 


49 


'M 

to  t 

•1 

d 

^ 

\ 

s 

x^ 

s 

s 

*x 

\ 

^0 

-> 

Vi^ 

s, 

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1 

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"Si 

—  . 

—  C. 

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s(\j 

s 

rv 

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-1 

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— 

^»u—  p- 


50  ELEMENTS  OF  DRAWING 

The  first  letter  to  be  drawn  is  the  capital  /,  and  the  bottom 
of  this  letter  is  to  be  located  23  spaces  from  the  top  edge  and 
14!  spaces  from  the  first  heavy  vertical  cross-section  line  on  the 
left  side  of  the  sheet. 

Having  satisfactorily  completed  the  outline  of  all  letters, 
clean  the  sheet  (see  page  17,  §  15),  and  go  over  all  lines,  making 
them  clear  cut  and  finished.  See  page  78,  §  54. 

Thoroughly  examine  the  work  to  see  that  nothing  has  been 
omitted;  correct  any  errors,  and,  after  the  sheet  has  been  in- 
spected, write  the  Date  Finished  and  the  Total  Actual  Hours  in 
the  title  form,  and  submit  the  sheet  for  final  approval. 

40.  The  Sloping  Ellipse.  A  large  number  of  capitals,  small 
letters,  and  numerals  of  the  inclined  Gothic  alphabet  have  an 
•outline  which  is  partly  or  entirely  oval.  This  oval  approaches 
:more  nearly  the  "sloping  ellipse"  than  any  other  curve,  and  the 
.beginner  should  understand  the  construction  of  such  a  curve  be- 
fore attempting  to  form  the  curved  letters.  The  exact  shape  of 
any  ellipse  is  determined  by  the  ratio  between  its  long  and 
short  axes.  Fig.  40 (a)  shows  an  ellipse  with  its  long  axis 
vertical  and  having  a  ratio  of  width  to  height  of  5  to  6,  this  ratio 
ibeing  common  to  many  letters.  This  ellipse  is  tangent  to  the 
guide  lines  at  the  points  i,  2,  3,  4,  and  is  symmetrical  about 
i>oth  the  long  axis  and  the  short  one.  Therefore  the  diagonals 
5  to  7  and  6  to  8  are  of  equal  length,  also  the  four  shaded  areas 
outside  the  ellipse  are  equal  and  have  the  same  shape. 

A  "sloping  ellipse"  is  shown  in  Fig.  40 (b).  In  this  con- 
struction the  long  axis  has  the  slope  of  the  alphabet  (2  to  i),  but 
the  short  axis  remains  horizontal.  When  this  curve  is  drawn  in 
a  parallelogram  and  is  tangent  at  the  extremities  of  the  axes, 
the  lines  i  to  3  and  2  to  4  do  not  divide  the  ellipse  symmetri- 
cally. The  shaded  areas  are  therefore  not  of  the  same  shape, 
but  those  diametrically  opposite  are  the  reverse  of  each  other. 
That  is,  in  the  sloping  ellipse  the  upper  left-hand  quadrant  of 
the  curve  is  the  same  as  the  lower  right-hand  quadrant  but 
reversed  in  relative  position,  and  similarly  the  upper  right-hand 
quadrant  is  the  same  as  the  lower  left-hand  quadrant  but  re- 
versed in  relative  position.  The  "  sloping  ellipse  "  is  therefore 


LETTERS,  NUMERALS,  AND  LETTERING 


not  of  the  true  ellipse  construction  but  is  an  ellipse  so  modified 
that  its  major  axis  has  the  slope  of  the  alphabet,  and  the  curve 
is  tangent  to  the  limiting  parallelogram  at  the  extremities  of  the 
In  certain  portions  of  the  outlines  of  some  of  the  capital 


axes. 


n  / 

\r 

/ 

£ 

[7.1*1 

•  y 

^T7 

^ 

/ 

A 

/  / 

6 

% 

A? 

y 

/ 

8' 

/' 

7> 

f 

P  i 

,: 

i 

\^ 

^^(j^w 

Cf.L.n 

r 

3 

/V 

£ 


?.L 


(a)  Vertical. 


(b)  Medium  Slope. 
Fig.  40.— Ellipses. 


(c)  Extreme  Slope. 


letters  and  in  the  case  of  certain  small  letters  a  much  better 
shaped  letter  is  obtained  if  the  slope  of  the  ellipse  is  made 
greater  than  the  standard  slope  as  shown  in  Fig.  4o(c).  Ap- 
proximately the  same  effect  can  be  obtained  in  some  of  the 
capital  letters  by  the  use  of  circular  arcs  as  shown  in  Z>,  U,  J, 
P,  B,  and  R,  pages  52  and  53.  The  use  of  the  small  ellipse  [see 
Fig.  4o(c)]  in  small  letters  is  shown  on  pages  63,  64  and  65. 

41.  Outline  and  Characteristics  of  Capital  (or  Upper-case) 
Letters  Composed  Wholly  or  Partly  of  Curved  Lines.  For  gen- 
eral discussion  of  guide  lines,  center  lines,  dimension  lines, 
and  arrows  as  used  in  connection  with  lettering  and  numbering, 
see  page  37,  §  34. 

Capital  O.  3  strokes.  Draw 
two  side-guide-lines  such  that 
their  distance  apart  is  equal  to 
the  width  of  the  letter.  Bisect 
the  parallelogram  by  two  center 
lines,  as  shown,  and  locate  the: 
points  of  tangency  of  the  guide 
^>*  lines  and  ellipse.  Draw  in  the 

sloping  ellipse  in  the  order  of  the  strokes.  For  full  description 
and  construction  of  the  "  sloping  ellipse "  see  page  50,  §  40. 
The  capital  Q  and  the  small  o  are  similar.  See  page  63. 


1 

/ 

1  _. 

/ 

/ 

Cs 

/ 

/ 

SI 

^ 

^ 

/ 

/^ 

/ 

/ 

V 

/ 

/ 

•/ 

/ 
$6 

7 

/ 

7 

/ 

/ 

i 

/ 

•s, 

/ 

/ 

x 

^--_ 

2] 

S 

P 

L. 

/ 

/ 

1 

u 

ELEMENTS  OF  DRAWING 


Capital  Q.  4  strokes.  Three 
strokes,  as  for  O.  (See  page  51.) 
#4  is  drawn  very  lightly  from  the 
left-hand  point  of  tangency  to  the 
intersection  of  the  right-hand  and 
bottom  guide  lines.  Erase  about 
two-thirds  of  the  left-hand  portion 
of  this  line  and  retrace  the  remain- 
ing portion  medium  weight. 


/  , 

/ 

/ 

/ 

L*-*1 

/ 

s 

/ 

// 

\ 

/ 

V 

/ 

/ 

/ 

/ 

7 

/ 

X 

' 

/ 

/ 

\v 

5 

s 

c 

/ 

i 

/ 

V 

^ 

^> 

/ 

T  

1 

7 

.  . 

X 

W  * 

Capital  C.     3  strokes.     Proceed 
as  with  O  (see  page  51),  excepting 
that  #2  and  #3  are  shortened.    The 
opening  in  the  ellipse  is  slightly 
greater  than  one-third  the  height  of 
letter  and  nearer  the  bottom  than  the 
top  guide  line  but  the  letter  width  is  the 
same  as  the  O.     The  capital  C  and  the  small  c 
See  page  64. 
4  strokes.    #i  and  #3 


t 

AJt 

^ 

NL 

/ 

C\j 

1 

Z§— 

\ 

/ 

t 

1 

/ 

/ 

/ 

/ 

"b, 

1 

/ 

/ 

/ 

, 

u 

/ 

s 

/ 

~^ 

& 

i 

'» 

V 

^ 

-'2 

^^^ 

/ 

/ 

/ 

/ 

are  similar. 
Capital  G. 

are  the  same  as  for  C.  (See  this 
page.)  #2  is  longer  than  #2  in  C  and 
extends  up  one-third  the  height  of 
letter.  $4  is  horizontal  and  extends 
one-third  across  the  letter. 


Capital  D.     3  strokes.     #i  is  standard 
slope.     The  right-hand  half  of  the  letter 
practically  the  same  as  the  right 
Eri:half  of  O.     (See  page  51.)     The  D 
is  slightly  narrower  than  the  O. 

Capital  U.    2  strokes.  ,^ 7 ^ 

Upper  half  of  letter  con-  j 


,  i  sists  of  standard  slope 
'  lines,  and  lower  half 
is  practically  the  same  as  lower  half 
of  O.  (See  page  51.)  The  U  is 
slightly  narrower  than  the  O. 


LETTERS,  NUMERALS    AND   LETTERING 


53 


^o 


T7 


F- 


Capital  J.  3  strokes.  S3  is  two- 
thirds  the  upper  portion  of  a  standard 
slope  line.  Note  that  /  is  relatively 

-  narrow.     The  lower  portion  of   the 
'   letter   is   part    of    a  small  modified 

-  sloping  ellipse.     See  page  50,  §  40, 
•i  Fig.  40  (c). 

P.     3    strokes.      #i   is 
fti 


- 

7 

----- 

* 

/I 

-<- 
/ 

^ 

>/ 

-m* 

_ 

i 

>i 

,.. 

eo|^ 

/ 

l 

\ 

v 

? 

T 

^ 

a 

-^ 

^/ 

i 

I 

\ 

\\ 

y 

1 

/ 

T 

1 

! 

/ 

I 

V 

-<  . 

_f 

-1 

/ 

— 

i 

i 
i 

•»—  i 

Ci 

3P 

ital 

_J  2  U-     Capital 

standard  slope.  S2  is 
partly  horizontal  and  partly  small 
modified  sloping  ellipse.  See  page 
51,  §  40.  Note  that  portions  of 

52  and  S3  are  parallel. 

Capital  R.     4  strokes.     #i,  #2,  and  S3  same  as 

Si,  #2,  and  S3  for  P.  (See  this  page.) 
S4  is  drawn  so  as  to  make  the  R 
r  wider  at  the  bottom  than  at  the 
top  and  should  be  drawn  in  such  a 
direction  that  it  would  intersect  Si 
(extended)  slightly  above  the  top 
guide  line.  , 

B.     4   strokes,     fti,  [    ~5 ^^ 
82,  and  part  of  S3  same  as  Si,  #2,  and 

53  for  P.     (See  this  page.)     The  lower 
half  (or  lobe)  of  B  is  of  the  same  form 
but  slightly  wider  than  the  upper  lobe. 

Capital   S.     3   strokes.      Draw  all 

guide  and  center  lines.     The  outline  of  the 

letter  consists  of  portions  of  two  tangent 

modified  ellipses,  exactly  the  same 
size  and  slope  but  in  reversed  rela- 
tive position.  Si  is  the  left  half  of 
upper  ellipse  and  the  right  half  of 
lower  ellipse.  #2  is  drawn  from  the 
top  point  of  tangency,  S3  to  the 
lower  point  of  tangency.  Locate 
accurately  the  seven  points  of 

tangency  before  "roughing  in"  ellipses  and  see  that  the  outline 


1 

- 

•*_ 

- 

y 

... 

«!•* 

/ 

/ 

2, 

Q 

*. 

'/ 

—*?. 

•*£ 

D 

/ 

/ 

i 

,  > 

7 

1 

f/ 

V 

f) 

T 

/ 

—  ^=- 

v~ 

^ 

'/ 

Jie 
>nt 

5, 

r~ 

—  2> 

k 

-<— 

54 


ELEMENTS  OF  DRAWING 


is  tangent  at  the  center  of  the  letter  but  is  not  drawn  below 
the  horizontal  center  line  at  the 
middle  of  the  letter.     The  capital 
and  the  small  s  are  similar.     See 
page  66. 

Abbreviation  &.  5  strokes.  #i, 
#2,  and  $3  are  almost  the  same  as 
for  the  numeral  8.  (See  page 
59.)  Note  especially  where  #4 
and  #5  begin  and  end. 

42.  Sheet  B.  The  purpose  of  this  sheet  is  to  teach  the  form 
and  characteristics  of  the  capital  letters  of  the  inclined  Gothic 
alphabet,  which  are  constructed  wholly  or  partially  of  curved 
lines,  and  to  give  practice  in  making  these  letters. 

Having  had  the  experience  of  making  sheet  A,  again 
read  paragraph  34,  page  37,  with  reference  to  the  Model 
letters. 

For  information  on  the  general  system  to  be  followed  see 
Appendix  A,  page  175. 

Exercises  on  Sheet  B.  These  exercises  include  all  capital 
letters  of  the  inclined  Gothic  alphabet  not  given  on  Sheet  A . 

Before  attempting  to  form  a  letter,  study  carefully  the  illus- 
tration and  description  of  that  letter  in  the  model  alphabet.  See 
page  51,  §41- 

Specific  Instructions  for  Executing  Sheet  B.  Tack  down  the 
sheet,  stamp  in  and  fill  out  the  title  form.  The  wording  in  the 
title  form  is  to  be  neatly  written  in  ink. 

The  title  of  Sheet  B  is  CAPITAL  LETTERS. 

Locate  the  letters  on  the  sheet  according  to  the  space  dimen- 
sions shown  in  Fig.  41 .  Proceed  with  the  lettering  systematically 
(seepage  44,  §  36)  and  complete,  as  shown  in  Fig.  41.  Having 
satisfactorily  completed  the  outline  of  all  letters,  clean  the  sheet 
and  retrace  all  lines,  making  them  clear  cut  and  of  the  desired 
weight. 

Carefully  examine  the  work  to  see  that  nothing  has  been 
omitted;  correct  any  errors,  and,  after  the  sheet  has  been 
thoroughly  inspected,  write  in  with  ink  the  Date  Finished 


LETTERS,  NUMERALS,  AND  LETTERING 


55 


*>r 


5 


i 


^ 


j£ 


.0). 


^ 


56  ELEMENTS  OF  DRAWING 

sand  Total   Actual   Hours,   and    submit    the    sheet    for    final 
approval. 

43.  Sheet  C.  The  purpose  of  this  sheet  is  to  teach  the  beginner 
to  correctly  maintain  all  relative  proportions  of  letters  and  spacing 
in  lettering  of  the  size  usually  found  on  practical  drawings. 

The  first  alphabet  at  the  top  of  the  sheet  is  reduced  to  one-half 
size;  this  means  that  dimensions  given  on  Sheet  A  (page  49, 
Fig.  39)  and  Sheet  B  (page  55,  Fig.  41),  including  the  spacing, 
are  reduced  one-half. 

The  second  alphabet  on  Sheet  C  is  reduced  to  one-third  size, 
and  the  unit  of  space  is  one- third  that  given  on  Sheets  A  and  B. 

The  lettering  in  the  note  at  the  bottom  of  Sheet  C  is  only  one 
space  high,  that  is,  it  is  one-sixth  size,  and  the  spacing  between 
letters,  words,  and  sentences  must  be  reduced  accordingly. 

Specific  Instructions  .for  Executing  Sheet  C.  Tack  down  the 
sheet,  stamp  in  and  fill  out  the  title  form. 

The  title  of  Sheet  C  is  REDUCED-SIZE  LETTERING. 

Locate  numbers  and  letters  on  sheet,  as  shown  in  Fig.  42. 

When  all  lettering  has  been  satisfactorily  completed  in  pen- 
cil, clean  the  sheet  and  retrace  all  lines,  making  them  the  proper 
weight. 

Every  possible  precaution  should  be  taken  to  prevent  soiling 
the  sheet  and  to  avoid  the  necessity  of  making  changes.  As  this 
sheet  is  to  be  inked,  any  erasing  which  tends  to  injure  the  sur- 
face of  the  drawing  makes  satisfactory  inking  very  difficult. 
This  sheet  must  be  finally  approved  in  pencil  before  it  is 
inked  in. 

Thoroughly  examine  the  work  to  see  that  nothing  has  been 
omitted;  correct  any  errors,  and,  after  inspection  and  approval, 
the  sheet  is  ready  for  inking.  Before  attempting  to  ink  any 
work  the  beginner  should  practice  inking  on  scrap  paper.  See 
page  136,  §  96.  Such  preliminary  practice  accustoms  the  hand 
to  the  touch  of  the  pen  and  avoids  experiments  on  approved 
penciled  sheets,  which  would  most  likely  spoil  them. 

Specific  instructions  for  Inking  Sheet  C.  Tack  down  the  ap- 
proved penciled  sheet  on  the  drawing  board  and,  before  be- 
ginning to  practice  inking  on  scrap  paper,  read  and  prepare 


LETTERS,    NUMERALS,  AND  LETTERING 


57 


-q- 


ELEMENTS  OF  DRAWING 


for  examination  on  the  following  paragraphs.  Free-hand  Inked 
Lines,  page  136,  §  96,  Drawing  Ink,  page  18,  §  18,  The  Ordinary 
Pen,  page  18,  §  19. 

44.  Outline  and  Characteristics  of  Numerals.  For  general 
discussion  of  guide  lines,  center  lines,  dimension  lines,  and  arrows 
as  used  in  connection  with  letters  and  numbers,  see  page  37, 
§34- 

/  Four.    3  strokes.     #i  is  standard 

slope  and  its  location  in  the  limiting 
parallelogram  of  guide  lines  is  very 
important,  being  a  distance  of 
three-fourths  the  total  width  of 
agure  from  the  left  guide  line.  #2 
Grlr. — extends  downward  two-thirds  the 
height  of  the  numeral.  #3  is  hori- 
zontal and  extends  entirely  across 
the  limiting  parallelogram  and  gives  the  figure  its  real  width, 
which  is  greater  than  any  other  numeral. 


V 

s 

1 

I 

! 

Q 

\ 

/N 

/ 

s 

/ 

' 

• 

- 

mmm' 

3 

->— 

/ 

Seven.  2  strokes.  Note  especially 
the  width  of  the  numeral,  the  curvature 
of  #2,  and  that  the  end  of  #2  does  not 
meet  the  bottom  guide  line  of  the 
limiting  parallelogram  equally  distant 
from  the  side  guide  lines. 

Naught.     3 


-4- 


f\  1 

^ 

I 

^m 

mar 

-7- 

j» 

/ 

• 

/ 

/ 

/ 

/ 

% 

/ 

/ 

Z 

'' 

1 

\ 

/ 

/• 

/ 

ft 

Crj 

,   / 

/ 

1 

/ 

o 

• 

/ 

1 

' 

/< 

^^ 

- 

^^ 

'• 

/ 

, 

) 

i 

/ 

r 

/ 

Ci 

1 

/ 

L 

: 

V 

/ 

u 

/ 

-y 

/ 

! 

V 

^ 

^ 

f 

', 

\c        '    r  ' 

strokes.     Formed   the  ' 
same   as   the  0    (see   page    51)   but 
slightly  narrower. 
Nine.     3 


-5f 


strokes.     A 
mall   sloping  ellipse 


[see  Fig.  40  (c)]  forms 
part  of  the  outline.     Note  especially 
the  angle  of  the  center  line  of  the  small 
ellipse  and  that  the  slope  of  the  portion  of  the  r* — 5 
large  ellipse  is  the  slope  of  the  numeral  [see  Fig.  40  (b)].    The 
form  of  the  Q  is  exactly  the  same  as  the  6  inverted  (see  page  59) » 


LETTERS,  NUMERALS,  AND   LETTERING 


59 


Six.  3  strokes.  The  form  of  the 
6  is  exactly  the  same  as  the  p  in- 
verted (see  page  58).  This  neces- 
sitates a  change  in  the  order  of 
strokes. 

Five.    4  strokes.    Lower  part  of  5 

is  similar  to  lower 

i  i 

ellipse  of  6  (see 

this  page) .  fti  is  standard  slope,  extend- 
ing to  ellipse  only.  Note  that  #i  is 
slightly  to  the  right  but  parallel  to  the 
left-hand  guide  line  and  therefore  is 
not  tangent  to  #2.  #4  extends  to  right 
guide  line.  Note  that  extreme  width  of  the 
numeral  is  from  starting  point  of  #2  to  right- 
hand  point  of  tangency.  ,  7  ,(  _.1_^\  i 
Eight.  4  strokes.  The  outline  of  the  numeral "?*]j  *  pT 
is  made  up  of  two  tangent  ellipses.  The 
lower  half  of  the  numeral  is  similar  in 
outline  to  the  upper  half  but  slightly  i 
wider.  Note  the  similarity  to  5  (see 

page  53). 

Three.    4  strokes,  j 
Consists  of  portions  •" 
of  two  ellipses  of  the  same  dimensions. 
Note  that  less  of  the  upper  ellipse  is 
used  than  the  lower ;  this  is  in  order  that 
the  numeral  will  not  appear  top  heavy. 
The  3  is  similar  to  the  8  (see  this  page). 
Two.     4  strokes. 
The  upper  half  of 

the  numeral   consists  of  part  of  an 

ellipse,  which  is  one-half  the  figure 

height  and  the  full  figure  width.     #i 

and  #3  are  both  tangent  to  left  guide 

line.     Note  the  curvature  of  #3  and  that 

begins  lower  down  than  on  the  numeral 

(see  this  page). 


60  ELEMENTS  OF  DRAWING 

45.  Sheet  D.    The  purpose  of  this  sheet  is  to  teach  the 
beginner   the   characteristics   of    the    numerals    and    to    give 
practice  in  making  them.     Locate  the  numerals  on  the  sheet 
as  shown  in  Fig.  43. 

The  slope  of  fractions  must  be  the  same  as  that  of  the  alphabet; 
for  example,  take  any  ordinary  fraction,  say,  five-eighths,  the 
eight  is  not  vertically  below  the  five,  but  a  standard  slope  line 
drawn  through  the  center  of  the  5  passes  through  the  center  of 
the  8.  The  line  separating  the  numerator  from  the  denominator 
must  always  be  a  straight  line  parallel  with  the  line  of  printing.  A 
sloping  dividing  line  may  lead  to  error  in  reading  a  fraction.  The 
figures  in  the  numerator  and  in  the  denominator  must  never 
touch  the  dividing  line.  The  total  height  of  a  fraction  should 
be  about  one  and  one-half  times  the  height  of  whole  numbers. 

Follow  specific  instructions  given  for  preceding  sheets  in  so  far 
as  they  apply  to  this  sheet. 

The  title  of  sheet  D  is  NUMERALS. 

46.  Sheet  E.    The  purpose  of  this  sheet  (see  Fig.  44)  is  to 
give  practice  in  lettering  of  a  size  suitable  for  notes  on  working 
drawings. 

Follow  specific  instructions  given  for  the  preceding  sheets  in  so 
far  as  applicable. 

The  title  of  sheet  E  is  LETTERING. 

Specific  Instructions  for  Inking  Sheet  E.  Tack  down  the 
approved  penciled  sheet  on  the  drawing  board,  and  carefully  ink 
each  letter  in  the  order  in  which  they  come.  Clean  the  pen 
frequently  and  maintain  a  steady  and  even  pressure  on  the  pen 
point.  Extra  care  must  be  taken  in  inking  this  sheet  other- 
wise it  is  liable  to  be  spoiled. 

47.  The  Small  (or  Lower-case)  Letters  of  the  Inclined  Gothic 
Alphabet.     In  studying  characteristics  of  the  lower-case  alphabet, 
carefully  read  §  34,  page  37,  and  remember  that  the  direction 
and  order  of  strokes  is  of  prime  importance.     As  in  the  case  of 
free-hand  capital  letters,  all  strokes  which  are  horizontal  or  nearly 
so  are  made  toward  the  right,  while  all  others  are  made  down- 
ward or  toward  the  draftsman.      This  avoids  the  possibility  of 
catching  the  pen  point  in  the  drawing  and  splashing  the  ink. 


LETTERS,    NUMERALS,    AND    LETTERING  6l 


Ss* 


ii 


62 


ELEMENTS    OF    DRAWING 


if 


* 


LETTERS,  NUMERALS,  AND  LETTERING 


This  alphabet  requires  a  total  height  of  eight  blocks  for  the 
model  letters,  but  in  practice  only  four  horizontal  guide  lines  are 
necessary.  These  lines  are  numbered  from  the  bottom  to  the  top. 
Thus,  #i  limits  the  letter  when  its  stem  (seepage  37,  §  34)  extends 
below  the  body  of  the  letter,  as  in  g,  j,  p,  q,  y;  $2  limits  the  bot- 
tom of  the  body;  #3,  the  top  of  the  body;  and  #4,  the  stems  when 
they  extend  above  the  body,  as  in  b,  d,f,  k,  h,  and  /.  The  distance 
between  the  first  and  second  lines  and  between  the  third  and 
fourth  lines  is  two  spaces,  or  one-half  of  that  between  the  second 
and  third  lines.  The  height  and  width  of  a,  c,  e,  n,  o,  u,  andfl  is 
the  same  and  is  equal  to  four  unit  spaces. 

The  letter  o  is  similar  to  the  sloping 
ellipse  described  in  §  40,  page  50,  and 
makes  up  wholly  or  partially  the  outline 
of  all  letters  having  a  body  more  or  less 
elliptical.  The  horizontal  and  the  slope 
guide  lines  form  a  parallelogram  and 
the  horizontal  center  line  intersects  these  guide  lines  at  their  mid- 
points, which  determine  the  touching  points  of  the  ellipse,  but 
the  sloping  center  line  runs  from  the  lower  left  hand  corner  to 
the  upper  right  hand  corner  [see  Fig.  40  (c),  page  51].  Thus  the 
small  oval  letters  "tilt"  more  than  the  capital  oval  letters,  though 
the  slope  of  the  letters  appears  the  same.  Consequently  the 
small  letters  are  more  in  harmony  with  the  capital  letters 
previously  described.  The  small  o  is  similar  to  the  capital  O 
(seepage  51). 

Letters  a,  d,  g,  and  q  differ  as  to  the  length  and  position  of  their 
stems.     All  these  stems   have  standard 
.,,,,_  slope  and  are  tangent  to  the  elliptical  body 

T7.LT          As^^^i'^JX/  f 
~~r?\/\W}~~      a^     e  same  corre~ 
•h**?felErffflB          sponding  point. 

-  -G.I.  The  vertical  height 


of  the  elliptical  J 

body  (or  lobe)  is 

equal  to  its  width  and  is  the  same  as  for 
the  o  (see  this  page).     The  body  of  the  a,          i       ^      \ 
d,  g,  and  q  should  be  made  with  two  strokes,  as  shown;  stroke 
#3  lies  along  the  slope  guide  line. 


64 


ELEMENTS    OF    DRAWING 


d  repeats  a,  except  that  stroke  #3  begins 
at  guide  line  #4. 

g    repeats    a   but  U — 4— *-j 

stroke   ft3  continues  ]/  ,          '/, 

with  a  sweeping 
curve  to  guide  line  fti , 

q  exactly 
the    a    construction 


but'stroke  #3  continues  to  guide  line  fti. 

The  stem  of  the  b 
is  the  first  stroke 
and  coincides  with 
the  left-slope 
guide  line;  stroke 
ft2  ends  at  the 
touching  point  of 
the  ellipse  and 
left-slope  guide  line;  stroke  ft3  continues  to  the  stem. 
p  differs  from  the  b  only  in  the  position  of  the  stem. 
Letters  c  and  e. 
Thee  has  the  same 
height  and  width  G.I 
as  the  o  (see  page 
63),  but  the  open- 
ing in  the  ellipse  is 
such  that  strokes 
ft2  and  ft3  begin  at  different  touching  points  on  the  right-slope 
guide  line.  The  small  c  is  similar  to  the  capital  C  (see 
page  52). 

The  e  differs  slightly  from  the  c  in  that  stroke  ft  2  ends  on  the 
horizontal  center  line;  stroke  ft4  starts  from  the  point  of  tangency 
of  stroke  fti,  and,  following  the  center  line,  joins  stroke  ft2. 

V  Letters  n,  r}  hj  and  m.  The  curved 
portion  of  the  n  consists  of  the  upper 
portion  of  the  ellipse  exactly  as  that  of 
the  u  consists  of  the  lower  portion  of 
'G.L.  the  o.  Stroke  fti  is  standard  slope; 
stroke  ft2  ends  where  the  ellipse  comes 


# 


/ 


-* 


y- 


LETTERS,  NUMERALS,  AND  LETTERING 

tangent  to  the  left-slope  guide  line,  and 
stroke  #3  follows  the  guide  line  from  the 
point  of  tangency.  Strokes  #i  and  #3  must 
be  parallel,  beginning  at  their  points  of 
tangency  with  the  ellipse. 

The  r  is  the  same  as  the  left  half  of  the 
n  except  that  stroke  #2  continues  along 
the  top  guide  line  a  short  distance. 

The  h  differs  from  the  n  only  in  the  length 
of  the  stem,  or  stroke  #i.     Note  that  though 
the  first  three  strokes  of  the   I     ? 
m  are  similar  to  those 
of  the  n,  the  width  is  1 
different;  strokes  #4  4 
#5  are  a  repetition  ofj 
#2  and  #3.      All  stems  are  parallel  and 

have  standard  slope.  H 6 H 

u  and  y.    The  curved  portion  of  "the  u  consists  of  the 
v  r* — 4— *\     lower  part  of  the 

n  .    ij  uc.        |_j  js  ellipse,  exactly  as 

G.I.T-      T»!   -"PT      -T-         VX*     tar  that  of  then  con- 


portion  of  the  o. 
Note  that  stroke 
#3   continues  to 
line  #2- 


t 

> 

1 

/^ 

>^ 

y 

1 
v*. 

N 

/ 

^ 

x 

^ 

/ 

// 

'*" 

<k 

2 

4- 

A' 

-S 

./ 

U- 

*    4-  - 

ff 

JT 

^ 

>, 

^ 

/ 

^ 

% 

^ 

1  ~t 

A 

2 

/ 

i 

2 

•^ 

^ 

r 

1 

t) 

^ 

^ 

S/ 

^ 

i  / 

CM 

7 

/ 

y  repeats  the  w,  but  stroke  #3  continues  to  guide  line  #i 
exactly  as  in  the  g.  (See  page  64.) 

ZcJfers  /,  *,  ^,  /,/,  andj.  The  /  is  a  simple  standard  slope  line 
drawn  toward  the  draftsman  and  is  six  spaces  high. 

The  i  is  a  single  stroke  of  standard  slope,  and  the  dot  is 
placed  exactly  where  the  stem  if  extended  would  cut  the  hori- 
zontal #4. 

The  k  has  a  standard  slope  line  as  stroke  #i;  stroke  #2  starts 
on  the  horizontal  guide  line  #3  but  to  the  left  of  the  slope  guide 
line,  so  that  the  latter  is  not  so  wide  at  the  top  as  at  the  bottom; 
stroke  #3  begins  below  the  middle  of  stroke  #2,  and  extends  to  the 


66 


ELEMENTS  OF  DRAWING 


horizontal  guide  line  #2,  giving  the  lower  part  of  the  letter  the 
standard  4-space  width. 


G.L- 


The  /  is  five  spaces  high  and  has  the  standard  slope.     Stroke 
$2  is  the  horizontal  cross-bar  which  coincides  with  horizontal 


i 


^ 


?->. 

b 

?- 

£ 

/ 

IT 

SN 

/ 

^  .g 

S 

/ 

t 

.m^ 

-2- 

/' 

I 

* 

/ 

/ 

1 

—  i       i 

/ 

1 

// 

/ 

\ 

h- 

^y 

_ 

1 

/' 

7 

/ 

' 

1  ~ 

I 

,/ 

//^ 

/ 

/i 

Q 

/ 

/ 

7 

j 

^X 

?'A 

*j 

2 

1 

^ 

7 

?* 

guide  line  #3  and  which  is  two  spaces  long  but  is  not  bisected 
by  the  stem  of  the  letter. 

The  /  repeats  the  t  except  that  by  adding  stroke  #3  the  letter 
is  brought  to  the  height  of  the  /. 

The.;  repeats  the  i,  but  is  carried  to  the  horizontal  guide  line 
#i  by  adding  a  curve  with  a  sweep  one-half  space  less  than  the 
tail  curve  of  the  g  and  that  of  the  y.  (See  pages  64  and  65.) 

Letter  s.  The  s  is  formed  in  three 
strokes.  Stroke  #i  is  a  double  and 
reverse  (ogee)  curve  which  is  horizon- 
tal at  the  top,  bottom,  and  the  middle 
_Q  ^  for  a  very  short  distance.  Strokes  #2 
and  #3  are  short  curves  from  left  to 
right.  If  the  bottom  oval  of  the 
letter  should  be  completed  it  would  be  four  spaces  wide,  while 
the  upper  oval  would  be  only  three  and  a  half,  thus  making  the 


LETTERS,  NUMERALS,  AND   LETTERING 


67 


letter  wider  at  the  base  than  at  the  top.     The  small  s  is  similar 
to  the  capital  S.     (See  page  53.) 

Letters  v  and  w.    The  v  contains  the  only  vertical  line  hi  this 
alphabet  which 
is  stroke  #i.    It 
has  full-letter  G'Lr 
width   of    four 
spaces    at   the 
top.   The  small  ^ 

.      «i  Cy     H« A — *"J  H*~w* 

v  is  similar  to 

the  capital  F.     (See  page  46.) 

Stroke  fti  of  the  w  is  not  the  same  as  stroke  #i  of  the  v,  nor 
is  it  twice  as  wide  as  the  v;  that  is,  the  w  is  not  made  up  of 
two  v's.  The  small  w  is  similar  to  the  capital  W.  (See  page  47.) 

Letter  x.     The  x  is  made  with  two 
strokes,  intersecting  slightly  above  the 
middle  of  the  sloping  center  line.  The  top 
is  three  and  a  half  spaces  wide,  while  the 
bottom  width  is   the  standard  four 


/ 


Q  . 

'  ' 


i 

1 

/ 

^7 

X 

"", 

X-i, 

1 

1^ 

^ 

/ 

', 

£ 

y 

/ 

I 

/ 

^mm 

—  c 

-~ 

/ 

;,         «r,  'spaces.  Note  that  this  slight  difference 

^.  ^    4~^\  in  top  and  bottom  width  is  the  same  with  the 
s  and  z.     The  smalls  is  similar  to  the  capital  X.    (See  page  46.) 

Letter  z.  The  z  is  made  up  of  three 
strokes.  The  top  and  bottom  of  the  letter 
have  the  same  widths  as  that  of  the  x 
and  s.  The  small  z  is  similar  to  the 
capital  Z.  (See  page  47.) 

48.  Sheet  F.  The  exercises  on  this  sheet 
(see  Fig.  45)  give  practice  in  making  the 

small  letters  of  the  Gothic  alphabet  and  afford  an  opportunity  to 
study  in  detail  the  characteristics  of  each  of  the  lower-case  letters. 
For  detailed  description  see  §  47,  page  60.  Note  especially  the. 
relative  size  of  capitals  and  numerals  used  with  this  alphabet. 

This  sheet  is  to  be  inked  but  is  to  be  perfected  and  approved 
in  pencil  before  inking  is  done. 

Follow  the  specific  instructions  given  for  preceding  sheets  as  far 
as  applicable. 

The  title  of  sheet  F  is  LOWER-CASE  LETTERS. 


68 


ELEMENTS  OF  DRAWING 


LETTERS,  NUMERALS,  AND  LETTERING  69 

49.  Designing  Headings  and  Titles.  A  very  quick  method 
of  laying  out  the  title  is  to  sketch  the  lines  of  lettering  on 
transparent  paper  of  good  quality  and  then  transfer  them  in 
their  proper  relative  position.  The  transferring  is  best  done  by 
blackening  the  back  of  the  paper  upon  which  the  lettering  is 
sketched,  using  a  soft  lead  pencil  sharpened  to  a  chisel  point  and 
held  flatwise.  The  paper  is  next  placed  in  its  proper  position 
on  the  drawing  and  the  outline  of  each  letter  carefully  traced 
over  with  a  moderately  sharp  pencil;  this  transfers  the  letters 
in  dim  lines.  These  outlines  will  not  be  so  true  as  the  original 
lines  and  must  be  gone  over  with  a  pencil  before  being  inked. 

After  a  little  experience,  a  simple  title  can  be  made  directly 
on  the  drawing  by  using  horizontal  guide  lines  and  arranging  the 
lettering  symmetrically  about  a  vertical  center  line.  This  letter- 
ing should  be  sketched  in  very  lightly  at  first,  and  when  correct 
the  entire  title  should  be  retraced  in  pencil  before  being  inked. 

When  lettering  a  drawing  if  a  name  or  a 
/          sentence  cannot  be  printed  in  a  horizontal 
&r  line,   the  proper  way  to  have  the  inclined 


lettering  read  is  shown  in  Fig.  46. 


50.   Sheet  G.     The  purpose  of  this  sheet 
(see  Fig.  47)  is  to  give  practice  in  laying  out 
Fig.  46-— Direction  in  the  bill  of  material  and  the  title  for  a  drawing. 
Before  beginning  work  on  _this  sheet  read 
carefully  §  49,  this  page.     This  sheet  is  graded 
upon  the  quality  of  the  lettering,  and  the  accuracy  shown  in 
locating  the  different  lines  of  lettering. 

Follow  specific  instructions  previously  given  in  so  far  as  appli- 
cable. 

NOTE.     The  straight  border  and  limiting  lines  of  the  title 
form  can  be  drawn  by  use  of  a  straight  edge,  but  they  should  be 
made  neatly  and  in  the  exact  location  as  shown  in  Fig.  47. 
The  title  of  sheet  G  is  TITLE  FORM. 

51.  Examination  on  Chapter  II.  Lay  out  a  sheet  of  vertical 
Gothic  letters  or  any  other  sheet  of  lettering  assigned.  Prepare 
for  examination  on  the  principal  subject  matter  of  this  chapter. 


70 


ELEMENTS  OF  DRAWING 


;a. 

IS 

JO  S 

8p: 

I 

i 

p 

1 

V 

1 

v,^^ 

1 

I 

1 

i 

i 

1 

r^ 

y 

3 

t- 

1 

X 

^ 

i 

r  N 

1 

U) 

i 

sl 

\ 

s 

L 

\ 

\ 

r 

N 

\ 

s 

S 

ry> 

r 

•J 

r\. 

1 

i 

QC 

Y 

LJ 

K 

\ 

<^ 

k 

^ 

[• 

v^ 

i  . 

I 

\ 

<v. 

( 

^ 

rr 

-X 

lr 

K 

\l 

k! 

X 

^ 

1 

i 

\ 

ri 

kl 

k 

s| 

^j 

-^ 

r 

-1 

n 

r\ 

? 

5 

(•  v 

g 

I 

. 

^ 

? 

v^ 

1 

rn 

rn 

x 

\ 

> 

k 

\\- 

C 

) 

y. 

1 

r-r 

rT 

kl 

I, 

r< 

S 

> 

r^ 

\ 

•- 

3 

\^ 

k 

tj 

k 

N 

2 

* 

2 

^ 

s 

§ 

pj 

A! 

ty 

I 

1 

IP 

Oi 

U 

y 

^J 

i"} 

l\l 

* 

^ 

T 

> 

Or 

\ 

< 

J) 

S 

( 

f) 

I 

i 

P 

s 

"N, 

V 

^ 

f/ 

•\ 

^ 

j 

( 

\ 

1 

j 

>. 

j 

± 

u 

J 

^ 

w 

1 

. 

1 

\ 

\ 

kl 

k 

4 

1 

^ 

| 

i 

\ 

^» 

p 

^J 

1, 

\ 

1 

I. 

1 

\ 

V 

^' 

1  1 

> 

1 

rv 

fX 

kj 

I 

n 

u 

v 

rl* 

to 

rn 

UJ 

ki 

j 

• 

r^ 

14  j 

fy 

3 

X 

v 

^j 

«• 

Ij 

y 

^ 

^> 

k 

( 

V 

* 

V 

D 

r 

>P 

2 

I 

~s» 

k 

' 

1 

} 

1 

**»» 

* 

- 

i 

s» 

f 

<i 

3  / 

CHAPTER  III 

MECHANICAL  DRAWING  AND  DRAFTING  ROOM 
PRACTICE 

52.  Introductory.  The  difficulty  of  describing  an  object  so  that 
its  form  and  proportions  can  be  completely  understood  and  the 
object  made  by  following  the  written  description  will  be  appre- 
ciated if  such  a  description  is  attempted  with  reference  to  some 
comparatively  simple  object.  The  art  of  drawing  is  made  use 
of  to  overcome  these  difficulties  and  drawing  might  be  considered 
a  "  short  hand  "  method  of  expressing  form  and  proportion.  The 
field  of  usefulness  of  drawing  is  very  broad  and  the  value  of  being 
able  to  draw  and  to  read  drawings  becomes  more  apparent  when 
it  is  realized  that  practically  all  buildings  and  construction,  as 
well  as  most  manufactured  articles,  were  planned  and  drawn 
before  their  construction  or  manufacture  was  started.  In  study- 
ing this  subject,  the  beginner  should  make  every  effort  to  become 
proficient  in  the  reading  as  well  as  in  the  making  of  mechani- 
cal drawings.  It  is  probable  that  most  persons  will  never  be 
called  upon  to  make  any  but  the  simplest  of  drawings,  but  all 
those  connected  in  any  way  with  engineering  work  must  be  able 
to  read  them,  and  the  ability  to  read  drawings  quickly  and  cor- 
rectly is  of  the  greatest  value.  There  are  several  branches  of 
drawing,  and  the  branch  to  which  the  reader  has  likely  become 
most  accustomed  is  perspective  drawing  or,  in  other  words,  draw- 
ings which  represent  an  object  in  a  single  view,  as  it  would  ap- 
pear to  the  eye  or  in  a  photograph.  A  perspective  drawing, 
however,  is  usually  difficult  to  make  and  does  not  offer  the 
possibilities  for  recording  dimensions  and  other  information  which 
is  often  necessary  to  the  engineer  and  which  can  be  easily  re- 
corded on  a  mechanical  drawing. 

A  mechanical  drawing  does  not  represent  an  object  by  a  single 
view,  as  it  would  appear  to  the  eye  or  in  a  photograph  but  repre- 
sents it  by  a  series  of  pictures  termed  " projected  views  "  which 

71 


ELEMENTS  OF  DRAWING 


will  be  explained  later.  Each  of  these  views  represents  some 
"  face  "  of  the  object  as  it  would  appear  if  it  actually  existed  in 
space,  its  appearance  assumed  to  be  unaffected  by  the  laws  of 
perspective.  See  §  53,  page  73. 

Briefly  stated,  a  mechanical  drawing  must  contain  complete 
and  absolutely  accurate  information  of  what  is  desired;  every 
line  on  the  drawing  should  be  a  fixed  and  measurable  distance 
from  every  other  line  and  should  stand  for  something  definite; 
the  views,  lettering,  and  dimensioning  must  be  well  arranged, 
and  neatly  and  accurately  done,  so  that  the  drawing  as  a  whole 
will  be  exactly  understood  and  present  a  pleasing  and  business- 
like appearance. 

When  lines  cannot  express  ideas  in  a  plain,  direct,  and  un- 
mistakable manner,  abbreviations,  symbols  and  printed  notes 
must  be  used  so  that  those  who  are  to  read  or  interpret  the 
drawing  will  be  in  possession  of  all  the  information  necessary  to 
carry  out  every  detail  of  the  designer's  or  draftsman's  wishes 
without  further  instructions,  either  written  or  spoken. 
•  In  just  so  far  as  a  drawing  fails  to  contain  all  necessary  infor- 
mation in  the  best  form  possible  it  is  unsatisfactory,  regardless 
of  how  well  it  may  conform  to  the  principles  of  mechanical  draw- 
ing or  the  degree  of  precision  and  elegance  with  which  it  has 
been  made. 

Symbols  on  a  mechanical  drawing  usually  consist  of  printed 
abbreviations  or  conventional  signs,  which  signs  are  more  easily 

drawn  than  the  true  form  of  the  object 
to  be  represented.  Thus,  instead  of 
representing  screw  threads  in  their  exact 
form,  as  shown  in  Fig.  48,  and  which 
would  be  difficult  and  tedious  to  draw, 
especially  on  a  small  scale,  the  conventional  method  of  rep- 
resenting ordinary  screw  threads,  as 
shown  in  Fig.  49,  is  widely  made  use 
of  in  practical  drawing  rooms. 

The  relation  of  parts  to  one  another,          13  Thds.  per  inch.  L.  H. 

-  f  .,          r       t     Fig.  49. — Threads  Conventionally 

processes   of    manufacture,   the   final  represented. 

finish  of  surfaces,  and  similar  data  are  indicated  by  notes, 

abbreviations  and  conventional  signs. 


Trued  Form. 


MECHANICAL  DRAWING  AND  DRAFTING  ROOM  PRACTICE      73 

The  printed  matter  consists  of  dimensions,  notes  of  instruction 
or  specifications,  names  of  parts,  titles,  and  similar  information. 

Each  of  these  three  divisions  —  the  drawing  of  the  views,  the 
application  of  conventional  signs,  and  the  composing  and 
printing  of  notes,  titles,  dimensions,  etc.,  — is  in  a  way  of  equal 
importance,  and  it  should  be  remembered  that  mechanical 
drawing,  as  it  is  generally  understood  and  applied,  especially  in 
the  manufacture  of  machinery,  etc.,  is  not  intended  to  produce 
artistic  effects,  but  to  give  instruction  and  to  convey  information 
of  a  definite  character  in  the  simplest  way  possible. 

53.  Projection  and  Projected  Views.  Mechanical  drawing 
is  based  upon  the  principles  of  orthographic  projection,  and  a 
knowledge  of  the  fundamental  principles  of  orthographic  pro- 
jection is  necessary  in  order  to  understand  even  the  simplest 
drawing.  A  short  discussion  is  given  here  and  a  more  extended 
discussion  of  this  subject  will  be  found  in  the  authors'  book  on 
"Elements  of  Descriptive  Geometry"  and  in  other  books  on  the 
same  subject. 

Orthographic  projection  consists  in  representing  the  form  of  an 
object  as  it  would  appear  if  projected  upon  two  or  more  planes 
(termed  planes  of  projection)  at  right  angles  to  one  another. 
The  projecting  is  assumed  to  be  done  by  rays  of  light  respec- 
tively perpendicular  to  these  planes  and  extending  from  the 
planes  to  the  points  on  the  object  being  projected. 

One  plane  of  projection  is  assumed  in  the  position  of  an  ordi- 
nary wall  (i.e.,  vertical)  and  is  termed  the  vertical  plane  of  pro- 
jection, the  other  occupies  a  position  corresponding  to  the  floor 
(i.e.,  horizontal)  and  is  termed  the  horizontal  plane  of  projec- 
tion. Both  vertical  and  horizontal  planes  of  projection  are  as- 
sumed to  be  transparent,  and  every  ray  of  light  which  extends 
from  the  vertical  plane  to  a  point  of  the  object  will  be  horizon- 
tal because  all  of  these  rays  are  perpendicular  to  the  vertical 
plane;  similarly  the  rays  which  extend  from  the  horizontal 
plane  to  the  object  will  be  vertical.  This  is  clearly  illustrated 
in  Fig.  50,  where  a  part  of  the  lathe  is  shown  projected.  The 
object  which  is  shown  projected  is  called  the  Tool  Rest  Sup- 
port Slide  and  is  shown  in  perspective  in  Fig.  112,  page  150. 


74 


ELEMENTS  OF  DRAWING 


A  careful  study  of  this  illustration  will  make  clear  the  process  of 
projecting  in  space.  To  produce  a  drawing  by  the  principles 
of  Orthographic  Projection  it  is  necessary  to  make  further  as- 
sumptions in  order  to  establish  a  relation  between  the  trans- 


Fig.  50.  —  Illustrating  the  Method  of  Orthographic  Projection 
by  the  Use  of  Transparent  Planes. 


(a)  —  Showing  the  Plan,  Front  and  Side 
Views  Brought  into  a  Single  Plane. 


0 

(b)  —  Arrangement  of  Views 
Ordinarily  Used  in  Making  a  Drawing. 


Fig.  31.  —  Usual  Relation  of  Views  on  a  Flat  Surface. 

parent  planes  at  right  angles  in  space  and  the  drawing  paper 
which  is  in  a  single  plane.  It  is  seen  that  the  object  is  behind 
the  vertical  plane  and  below  the  horizontal  plane,  and  this  is 
termed  third  angle  projection. 


MECHANICAL  DRAWING  AND  DRAFTING  ROOM  PRACTICE      75 


Assume  that  after  the  views  of  the  object  are  projected 
upon  the  planes  these  planes  are  unfolded  so  as  to  be  brought  to 
a  single  plane  or  flat  surface,  as  shown  in  Fig.  51.  This  opera- 
tion brings  the  top-view  above  the  front-view,  and  the  right- 
side-view  to  the  right  of  the  front-view.  By  connecting  projec- 
tions of  corresponding  points  of  the  different  views  with  straight 
dashed  lines  (as  shown),  it  will  be  found  that  these  lines  are 
perpendicular  to  the  lines  (G-L  and  Gi-Li)  which  mark  the  edges 
of  the  planes  of  projection.  These  dashed  lines  serve  to  connect, 


(a)  —  Showing  Plan  and  Front  Views  "  Folded 
the  Plane  of  the  Side  View. 


into 


(b)  —  Showing  Front  and  Side  Views  "  Folded  "  into  the  Plane  of  the  Plan  View. 
Fig.  52.  — Various  Arrangements  of  Views. 

from  one  view  to  another,  points  which  are  projections  of  a  single 
point  on  the  object  represented.  They  are  the  same  length  as  the 
projecting  rays  of  light  and  represent  them  on  the  drawing  paper. 
The  relative  position  of  the  different  views  as  shown  in  Fig.  51 
is  a  very  common  arrangement  in  practice,  but  the  arrange- 
ments of  views  as  shown  in  Fig.  5  2  (a)  and  52(b)  are  equally 
correct  and  may  be  used  if  for  any  reason  they  are  found  more 
convenient.  The  top  view  is  known  as  the  plan,  and  the  side 
or  front  views  as  the  side  elevation  or  front  elevation. 


76  ELEMENTS  OF  DRAWING 

54.  Conventional  Lines.  If  all  the  lines  of  a  drawing  were 
identical  in  character,  that  is,  unbroken  throughout  their 
length  and  of  the  same  weight,1  the  drawing  would  be  lacking  in 
contrasts  and  would  be  difficult  to  read.  This  difficulty  is 
overcome  by  using  lines  of  different  construction  and  weight 
for  different  purposes.  For  example,  solid  unbroken  lines 
(called  "visible  lines")  of  fair  width  are  used  to  represent 
visible  parts  of  an  object;  fine  lines  (called  "invisible  lines") 
composed  of  short  dashes  are  used  to  represent  invisible  parts. 
Dimension  lines  are  unbroken  (except  for  the  dimension  figures) 
but  are  not  so  prominent  as  the  lines  representing  visible  out- 
lines of  the  object. 

The  meaning  of  the  construction  of  the  various  lines  is 
given  below,  but  no  single  rule  can  be  stated  as  to  the  proper 
weight  of  the  different  classes  of  lines  since  this  depends  on 
circumstances. 

The  visible  line  is  an  unbroken,  heavy  line  used  to  represent  the 
outline  of  the  object  and  the  surfaces  that  are  in  full  view 

Fig.  53-  —  "  Standard  "  Visible  Line. 

of  the  draftsman.  The  weight  of  the  line  must  be  varied  at 
times,  depending  on  the  size  and  the  accuracy  required  of  the 
drawing,  but  the  standard  weight  is  shown  in  Fig.  53. 

The  invisible  line  is  used  to  represent  the  parts  of  an  object 
which  are  hidden  or  invisible  to  the  draftsman.  Such  lines  are 
broken  into  short  dashes  about  one-eighth  inch  long,  separated 
by  spaces  of  one-half  this  length,  and  are  only  about  two- thirds 

Fig.  54.  —  "  Standard  "  Invisible  Line. 

the  weight  of  the  visible  lines.  When  an  invisible  line  is  very 
short,  the  dashes  and  spaces  must  be  shortened  accordingly. 
Dashes  must  be  made  of  one  length  and  spaces  of  another,  the 
spaces  always  being  smaller  than  the  dashes  (see  Fig.  54). 

1  The  weight  of  the  line  determines  its  prominence.  Variation  in  weight 
is  secured  by  making  the  line  of  different  widths  if  drawn  with  ink,  and 
by  making  it  lighter  or  darker  in  color  by  varying  the  pressure  and  hard- 
ness of  the  lead  if  drawn  with  a  pencil. 


MECHANICAL  DRAWING  AND  DRAFTING  ROOM  PRACTICE      77 

Section  lines  (see  Fig.  55)  are  drawn  parallel  and  usually  close 
together  (say,  Ty  to  |")  and  covering  those  areas  which  are 
assumed  cut  and  exposed  to  view.  They  are  light  weight  con- 
tinuous lines  in  construction.  (See  Fig.  63,  page  81.) 

Fig-  55.  —  "Standard"  Section  Line. 

Dimension  lines  (see  Fig.  56)  are  for  the  purpose  of  indicat- 
ing the  limits  between  which  dimension  figures  apply.  Dimen- 
sion lines  are  drawn  light  weight  and  are  unbroken  except  for 

-  -  /Q-  -  _ 


2 

Fig.  56.  —  "Standard"  Dimension  Line. 

a  distance,  usually  in  the  center,  to  allow  for  the  dimension 
figures.  Under  no  circumstances  should  this  line  pass  through  the 
dimension  figures. 

An  arrowhead  is  drawn  at  the  end  of  a  dimension  line  to 
indicate  its  extremity  and  the  place  to  which  the  dimension 
applies. 

Arrowheads  appear  much  better  when  drawn  long,  sloping, 


(a)    Correct.  (b)   Incorrect. 

Fig.  57.  —  Arrowhead. 

and  narrow,  as  shown  by  Fig.  5 7 (a),  and  they  should  not  be 
drawn  spreading,  as  shown  by  Fig.  57(b). 

Reference  lines  extend  out  from  a  part  to  be  dimensioned  to 
receive  the  arrowheads  at  the  ends  of  the  dimension  lines.  They 
consist  of  groups  of  three  dashes  —  two  short  and  one  long  — 
repeated  as  often  as  necessary  to  make  the  line  as  long  as  re- 


Fig.  58. —  "Standard"  Reference  Line. 

quired.  The  line  should  begin  with  the  two  short  dashes  and 
end  with  the  long  one,  and  the  relation  between  short  dashes, 
long  dashes,  and  spaces  is  the  same  as  in  center  lines.  (See  page 
78.)  A  short  space  should  always  separate  the  reference  line  from 
the  object.  Fig.  58  shows  the  standard  reference  line. 


78  ELEMENTS  OF  DRAWING 

The  center  line  is  a  line  around  which  a  sketch  or  drawing 
is  "built,"  and  is  usually  an  axis  of  symmetry.  It  is  composed 
of  short  and  long  dashes.  The  short  dashes  are  about  one- 
eighth  inch  long,  and  the  length  of  the  long  dashes  will  depend 
on  the  size  of  the  drawing.  The  space  separating  long  and 
short  dashes  is  about  one-sixteenth  inch.  (See  Fig.  59.) 


Fig.  59-  — "Standard  "  Center  Line. 

The  center  line  of  a  part  not  detailed  is  often  shown  on  a 
drawing  in  its  true  relative  position  to  the  parts  that  are  drawn. 
In  such  a  case  the  symbol  <£_  is  written  across  the  center  line  of 
the  part  not  detailed,  but  this  symbol  is  not  used  on  center 
lines  of  parts  that  are  drawn.  Thus,  on  part  No.  i  of  drawing 
C-ioi  (see  page  118,  Fig.  82)  the  center  line  of  the  shaft  is  not 
marked,  but  the  positions  of  the  bearings  are  located  by  drawing 
their  center  lines  and  marking  them  ^  OF  BEARING. 

Some  drawings  do  not  require  center  lines,  while  others  may 
require  several,  depending  usually  on  the  number  of  axes  of 
symmetry.  The  center-line  construction  is  also  used  to  indicate 
the  location  of  a  cutting  plane  in  making  a  cross-sectional  view, 
and  the  two  should  not  be  confused. 

All  finished  lines,  whether  drawn  free-hand  or  mechanically, 
with  pencil  or  with  ink,  must  be : 

(a)  Clear  cut. 

(b)  Free  from  waves. 

(c)  Of  the  same  width  throughout. 

(d)  Colored  to  the  same  degree  throughout. 

A  line  is  clear  cut  when  the  edges  are  free  from  irregularities, 
that  is,  when  the  outer  edges  are  not  "  ragged  "  or  "  sketchy." 

A  line  is  free  from  waves  when  it  does  not  deviate  locally 
from  the  general  direction  it  should  follow.  Both  the  wavy  and 
the  ragged  free-hand  lines  usually  result  from  holding  the  pencil, 
or  particularly  the  pen,  with  such  a  tense  grip  as  to  cause  the 
hand  to  tremble.  Hold  the  pencil  or  pen  easily,  as  you  would 
in  ordinary  writing. 

A  line  is  of  unvarying  width  when  the  outer  edges  run  paral- 
lel throughout  its  length. 


MECHANICAL  DRAWING  AND  DRAFTING  ROOM  PRACTICE       79 

A  line  is  colored  to  the  same  degree  (i.e.,  of  even  color)  when 
the  coloring  matter  (such  as  lead  or  ink)  is  evenly  distributed 
throughout  the  line.  To  avoid  making  a  pencil  or  ink  line 
appear  dark  at  one  point  and  light  at  another,  that  is,  variable  in 
degree  of  color,  apply  even  pressure  in  making  the  finished  line, 
and  in  inking  maintain  a  uniform  flow  of  ink  by  frequently 
cleaning  and  refilling  the  pen. 

55.  Sectioning  and  Sectional  Views.  If  an  object  has  hollow 
portions  it  is  often  necessary  to  know  the  exact  form  and  the 
dimensions  of  the  interior. 

Since  invisible  portions  of  an  object  are  represented  on  draw- 
ings by  means  of  broken  lines,  views  which  represent  the  exte- 
rior or  visible  portion  and  at  the  same  time  attempt  to  show  the 
interior  form  of  an  object  are  frequently  complicated  and  hard  to 
read.  To  overcome  this  difficulty  it  is  often  convenient  to  im- 
agine the  object  cut  open  with  a  saw  [see  page  80,  Fig.  60 (a) 
and  60  (b)]  and  then  represent  it  as  if  the  plane  of  the  cut  MN 
were  an  outside  surface  of  the  object.  [See  Fig.  6o(c).] 

Such  a  view  of  an  object  is  termed  a  sectional  view,  a  cross 
section,  or  simply  a  section  of  the  part.  If  a  section  is  taken 
in  the  direction  of  the  length  of  an  object,  it  is  termed  a  longi- 
tudinal section;  if  taken  perpendicular  to  the  length,  it  is  termed 
a  transverse  section. 

A  complete  section  is  not  always  assumed  in  a  single  plane,  but 
may  be  made  up  of  partial  sections  in  several  planes.  A  built- 
up  cross  section  is  intended  to  give  information  in  such  a  way 
as  to  make  it  unnecessary  to  draw  several  cross-sectional  views 
or  perhaps  a  complete  view  of  the  object.  In  Fig.  61  the  cut- 
ting planes  move  along  the  line  HPST  and  the  section  should 
be  referred  to  as  the  section  HPST. 

The  method  of  accurately  determining  complicated  sections 
in  true  projection  is  beyond  the  scope  of  this  work  and  is  ex- 
plained more  fully  in  the  authors'  book  on  "  Descriptive  Geom- 
etry "  and  in  other  books  on  the  same  subject. 

In  order  to  make  sectional  views  easily  understood,  the  dif- 
ferent kinds  of  material  assumed  to  be  cut  are  sometimes  in- 
dicated on  the  drawing  by  conventional  methods.  The  usual 


8o 


ELEMENTS  OF  DRAWING 


u 

•a  o 


II 

I! 


MECHANICAL  DRAWING  AND  DRAFTING  ROOM  PRACTICE      8 1 


method  is  termed  sectioning  and  consists  of  various  combina- 
tions of  spacing,  and  light  and  heavy  weight  lines  drawn  parallel 
and  covering  the  area  which  represents  the  surface  assumed  to 
be  cut  and  exposed  to  view.  No  uniformity  exists  in  practice 
as  to  the  combination  of  lines  and  spaces  that  shall  represent  a 
particular  material.  Those  combinations  given  in  Fig.  62  are 
fairly  general  in  their  application,  but  it  is  readily  seen  that, 
because  of  the  great  variety  of  materials  in  use  and  the  fact  that 


CAST  IRON 


WROUGHT  IRON 


(a)  Ordinary  Sectioning,    (b)    Sectioning  Adjoining 

Pieces. 


Fig.  62.  —  "  Conventional  "  Sectioning. 

new  materials  are  constantly  being  introduced,  it  is  better 
practice  to  use  only  the  simple  parallel  lines  [see  Fig.  63  (a)] 
and  then  designate  the  ma- 
terial by  writing  its  abbre- 
viation (see  page  103,  §  67) 
on  the  ruled  surface  or  in 
some  other  simple  manner. 
Where  a  number  is  used  Fig.  63.— sectioning. 

to  indicate  a  material,  it  has  the  advantage  that  the  number  can 
also  represent  the  quality,  heat  treatment,  etc.,  or,  in  the  case 
of  alloys,  the  composition.  The  number  therefore  does  not 
only  represent  the  name  of  the  material  but  also  its  properties  — 
both  physical  and  chemical  —  and  in  reality  is  a  specification 
number.  A  further  advantage  of  this  method  is  that,  should 
the  material  originally  called  for  prove  unsatisfactory,  as  is 
frequently  the  case,  a  change  in  the  number  can  be  made  on 
the  drawing  without  erasing  the  section  lines. 


82  ELEMENTS  OF  DRAWING 

Section  lines  of  adjoining  pieces  [see  Fig.  63  (b)]  are  drawn 
in  different  directions,  if  possible,  so  as  to  more  clearly  define 
the  limits  of  the  parts. 

Section  lines  should  be  drawn  at  45°  to  the  horizontal  when- 
ever possible,  and  should  be  made  about  one-half  the  weight  of 
the  lines  used  to  represent  the  outline  of  the  section.  To  section 
an  area  evenly  requires  practice  and  a  steady  hand.  Beginners 
usually  make  the  mistake  of  drawing  the  section  lines  too  close. 
Also  the  tendency  is  to  vary  the  distance  between  section  lines, 
usually  increasing  the  spacing  as  the  work  proceeds.  Such  sec- 
tioning is  unsatisfactory,  and  can  be  avoided  by  glancing  back 
over  the  completed  area  for  each  eight  or  ten  lines  drawn,  thus 
bringing  to  mind  the  original  unit  of  spacing.  If  a  section  line 
has  been  drawn  too  far  from  the  preceding  one,  the  next  line 
should  be  drawn  at  a  distance  less  than  the  unit  spacing;  this 
has  the  effect  of  giving  an  even  appearance  and  the  normal 
spacing  should  then  be  continued. 

The  spacing  between  section  lines  should  be  TV'  to  £",  depend- 
ing upon  the  size  of  the  cross  section,  but  must  be  the  same 
throughout  the  area  of  any  single  part  being  represented  in  sec- 
tion. To  insure  uniform  spacing,  draftsmen  sometimes  use 
section  liners.  The  simplest  form,  and  one  easily  made,  is 
shown  in  Fig.  64.  It  consists  of  a  small 
straight-edge  cut  out  to  receive  one  side 
of  the  triangle.  The  length  of  the  slot 
portion  is  equal  to  the  length  of  the  side 
of  the  triangle  plus  the  approximate 
. —  S£CT/0"Lmr*  I  .  distance  desired  between  the  section 

^       STRAIGHT  EDGE  OF 

^  T-SQUARE  BLADE  \  lines.  To  use  this  device,  place  it  on 
Fig.  64.  — section  Liner.  fae  drawing  with  the  triangle  against 
the  left-hand  stop,  as  shown  in  Fig.  64;  draw  a  line  along 
the  slope  side;  hold  the  triangle  stationary  with  the  fingers  of 
the  left  hand,  and  with  the  thumb  move  the  strip  to  the  left 
until  it  is  stopped  by  the  triangle.  Next  hold  the  strip  sta- 
tionary and  slide  the  triangle  until  it  comes  in  contact  with 
the  left-hand  stop  of  the  strip,  and  draw  the  second  line.  This 
process  is  repeated  until  the  sectioning  is  completed.  When 
the  section  is  very  large,  the  section  lining  is  sometimes  placed 


MECHANICAL  DRAWING  AND  DRAFTING  ROOM  PRACTICE     83 

at  the  edges  only,  as  this  saves  time  and  usually  gives  a  better 
appearance ;  in  such  cases  the  distance  between  the  section  lines 
would  be  increased  somewhat. 

Sectional  views  may  be  drawn  in  any  suitable  position  on 
the  drawing,  but  it  is  always  best  to  locate  them  as  close  to  the 
place  at  which  they  are  taken  as  is  convenient.  To  indicate 
the  location  of  the  section,  a  line  must  always  be  drawn  across 
the  original  view  of  the  object,  and  the  extremities  of  the  line 
(which  represents  the  cutting  plane)  should  be  lettered  as  shown 
in  Fig.  85,  page  123. 

It  is  not  always  necessary  to  draw  the  cross  sectioning  over 
the  entire  surface  that  lies  within  the  cutting  plane,  and  in 
general  such  details  as  a  shaft,  key,  bolt,  gear  tooth,  rib  or  arm 
of  a  wheel,  are  not  sectioned. 

Where  a  part  shown  in  section  is  symmetrical  about  a  center 
line,  such  as  a  part  turned  on  a  lathe,  a  half  or  a  quarter  longi- 
tudinal section,  together  with  an  end  view,  is  often  the  best  choice 
of  views.  Thus,  a  drawing  of  the  Tail  Stock  Spindle  (see  Fig. 
103,  page  144)  or  the  Shell  (see  Fig.  104,  page  144)  would  usually 
consist  of  an  end  view  and  a  top  or  side  view  shown  in  section; 
that  is,  the  Spindle  is  assumed  to  be  sawed  in  two  lengthwise, 
the  front  or  top  half  removed,  and  a  drawing  made  of  the  remain- 
ing half  as  it  appears  when  looking  directly  at  the  cut  surface. 

When  a  drawing  is  made  of  an  object  assumed  to  be  so  cut 
that  one-fourth  of  the  piece  is  removed,  the  view  is  termed  a 
quarter-section  view. 

Sometimes  by  turning  up  a  section  directly  on  the  first  view 
space  is  saved  and  a  second  view  of  a  part  is  unnecessary.  In 
such  cases  all  the  lines  of  the  original  view  must  be  drawn  in, 
even  though  they  may  conflict  somewhat  with  the  lines  of  the 
turned  up  section.  (See  Key  shown  in  Fig.  82,  page  118.) 

56.  Number  and  Arrangement  of  Views.  There  is  always  a 
choice  of  views,  and  those  views  should  be  made  which  convey 
the  greatest  amount  of  information  consistent  with  clearness. 
In  determining  the  number  of  views  required,  the  purpose  of 
the  drawing,  the  form  of  the  object  drawn,  and  the  character  of 
the  views  must  all  be  considered.  The  rule  to  be  followed  as 


84  ELEMENTS  OF  DRAWING 

to  the  number  of  views  is  that  there  shall  be  the  least  number 
made  to  accomplish  the  purposes  of  the  drawing.  In  general, 
three  views  of  an  object  are  sufficient  to  illustrate  its  form  and 
the  processes  necessary  in  its  manufacture.  If,  however,  its 
construction  is  complex,  it  may  require  sectional  views  in  ad- 
dition to  the  three  general  views  'ordinarily  taken.  If  the  part 
is  quite  simple  and  symmetrical,  —  as,  for  example,  a  washer, 
bolt,  screw,  shaft,  plain  key  (see  Fig.  82,  page  118),  —  a  single 
view  is  sufficient.  The  draftsman  should  imagine  himself  read- 
ing the  drawing,  and  make  as  many  views  (and  no  more)  as 
are  necessary  to  give  complete  information  in  a  clear  and 
unmistakable  manner.  While  making  or  checking  a  drawing  if 
the  question  arises  as  to  whether  certain  views  or  cross  sections 
-are  needed  in  order  that  the  drawing  may  convey  all  information 
necessary,  these  views  or  sections  should  always  be  drawn,  for 
it  is  reasonable  to  assume  that  any  point  of  uncertainty  not  fully 
cleared  up  by  the  draftsman  or  checker  leaves  the  way  open  for 
those  using  the  drawing,  especially  for  the  first  time,  to  make 
mistakes.  An  effort  on  the  part  of  the  draftsman  or  checker  to 
rush  work  or  "save"  time  often  leads  to  costly  errors  on  the  part 
of  those  who  must  work  with  the  drawing,  besides  causing  a  loss  of 
time  by  each  person  who  must  read  the  drawing.  A  note  should 
be  used  when  it  will  save  drawing  a  view.  In  general,  several  sec- 
tions are  preferable  to  a  single  view  containing  many  dashed  lines. 

The  arrangement  of  the  views  must  be  such  that  their  relation 
to  one  another  will  be  what  is  technically  termed  third-angle  pro- 
jection (see  page  74,  §  53).  Sectional  views  and  other  auxiliary 
views  should  be  placed  close  to  the  main  view  of  the  part  which 
they  partially  represent. 

Where  practical  the  main  views  of  an  object  should  represent 
it  in  a  similar  position  to  that  which  it  will  occupy  on  the  ma- 
chine, that  is,  a  part  should  not  be  represented  upside  down,  etc. 

The  different  views  should  be  arranged  symmetrically  on  the 
sheet,  in  order  that  space  may  be  used  to  the  best  advantage  and 
that  the  drawing  as  a  whole  may  present  a  pleasing  appearance. 

This  can  be  accomplished  best  by  blocking  out  the  sheet 
with  free-hand  rectangles,  drawn  to  scale,  to  include  each  view 
(see  page  93,  §  61).  These  should  be  sketched  in  very  lightly, 


MECHANICAL  DRAWING  AND  DRAFTING  ROOM  PRACTICE     85 

and,  after  provision  has  been  made  for  all  the  views,  if  the  rec- 
tangles are  not  well  distributed  they  can  be  easily  rearranged. 

57.  Detail  Drawings.  A  detail  drawing  is  one  which  repre- 
sents a  single  part  and  contains  all  information  necessary  for  its 
manufacture.  Before  a  detail  drawing  is  made,  therefore,  an  ex- 
perienced draftsman  will  determine  exactly  and  to  the  minutest 
detail  the  purpose  of  the  finished  part  and  the  shop  operations 
necessary  to  produce  it.  It  often  occurs  that  the  draftsman 
knows  exactly  what  is  wanted  in  the  finished  part  but  has  not 
had  sufficient  shop  experience  to  know  the  best  method  of  produc- 
ing it.  In  such  cases  this  information  should  be  obtained  from 
a  reliable  source  before  the  drawing  is  carried  too  far.  Generally 
a  single  detail  drawing  serves  for  all  departments  of  a  manufac- 
turing plant,  but  it  may  happen  in  complex  work  that  different 
details  are  required  for  the  different  classes  of  workmen,  such 
as  the  pattern  maker,  the  blacksmith,  the  machinist,  etc.  Such 
drawings  give  the  dimensions  and  notes  required  only  by  the 
particular  class  of  workmen  for  whom  they  are  intended. 

The  number  of  parts  detailed  on  a  single  sheet  will  depend 
on  circumstances,  but  it  is  becoming  more  common  to  detail  each 
part  on  a  separate  sheet.  This  method  has  the  advantage  that 
fewer  workmen  are  affected  in  case  a  drawing  has  to  be  recalled 
for  any  reason.  Also,  as  the  drawing  can  be  easily  and  quickly 
obtained,  the  chances  of  costly  mistakes  are  lessened  in  case  a 
change  must  be  made  on  a  part.  In  cases  where  an  article  is 
standard  and  is  produced  in  great  quantity  it  is  sometimes 
advisable  to  represent  a  part  on  several  sheets  called  operation 
sheets,  that  is,  a  drawing  which  shows  only  the  operation  to 
be  performed  on  the  part  by  a  single  workman.  In  establish- 
ments where  a  system  of  representing  several  parts  on  a  single 
sheet  is  practiced  it  is  customary  to  group  parts  in  a  logical 
manner;  for  instance,  parts  which  fit  together  may  be  detailed 
on  the  same  sheet,  say,  in  the  case  of  the  lathe  the  details  of  the 
Headstock  might  make  up  one  sheet;  parts  made  of  the  same 
material,  such  as  cast-iron  parts,  might  be  grouped;  or  parts 
which  are  manufactured  by  similar  processes,  and  hence  in  the 
same  shop  department,  are  detailed  on  the  same  sheet.  If  parts 


86  ELEMENTS  OF  DRAWING 

which  fit  together  are  detailed  on  the  same  sheet  they  are  more 
easily  checked,  but  in  practice  it  is  often  difficult  to  maintain  a 
fixed  system  of  grouping.  Certain  advantages  are  to  be  gained 
by  the  beginner  in  grouping  detail  drawings  and  hence  several 
parts  will  be  shown  on  a  single  sheet  in  this  course  rather  than 
each  part  drawn  on  a  separate  sheet. 

In  making  a  detail  drawing,  roughly  "block  out"  in  very 
light  lines  the  different  views  in  their  approximate  relative  loca- 
tion on  the  sheet  before  beginning  the  actual  pencil  drawing. 

It  is  usually  better  to  work  up  all  the  views  of  a  part  at  the 
same  time  rather  than  to  endeavor  to  complete  one  view  and 
then 'pass  to  the  next.  As  a  rule,  one  part  should  be  detailed 
completely,  including  all  its  views,  dimensions,  notes,  etc., 
before  the  detailing  of  another  part  is  started. 

58.  Assembly  Drawings.  The  detail  drawings  show  the  form 
and  size  of  each  part  but  give  no  idea  how  the  various  parts 
fit  together  or  how  the  machine  or  structure  as  a  whole  will 
appear.  The  assembly  drawing  illustrates  the  general  design 
of  a  machine  or  structure  and  contains  information  which  en- 
ables a  workman  to  sort  out  the  finished  parts  and  assemble 
them  into  the  machine.  The  assembly  drawing  is,  therefore,  a 
representation  of  the  completed  machine  or  structure  with  all 
its  parts  collected  and  arranged  in  their  proper  relation  to 
one  another.  //  should  be  drawn  part  by  part  from  the  detail 
drawings  and  serves  as  a  last  check  that  all  parts  fit  together. 
Such  drawings  may  show  some  detail,  but  too  much  of  the  inside 
construction  should  not  be  shown  (in  dashed  lines)  or  the  drawing 
may  be  difficult  to  read.  If  the  machine  is  complex  two  or  more 
views  and  cross  sections  through  several  parts  may  be  required, 
in  order  to  give  all  necessary  information  and  still  avoid  too 
much  dashed-line  construction.  Such  minor  parts,  as  bolts,  nuts, 
screws,  keys,  etc.,  are  seldom  drawn  in  detail  upon  the  assembly 
drawing,  but  their  position  is  usually  indicated  by  center  lines. 

Only  over-all  and  important  main  dimensions  should  be 
given  on  assembly  drawings.  It  sometimes  adds  to  the  value 
of  an  assembly  drawing  to  give  parts  a  reference  number  or 
letter  so  that  they  can  be  easily  referred  to.  See  page  104,  §  69, 


MECHANICAL  DRAWING  AND  DRAFTING  ROOM  PRACTICE       87 

59.  Conventional  Methods.  As  has  been  stated  elsewhere, 
the  purpose  of  a  mechanical  drawing  is  to  give  instruction  and 
information,  and  not  to  produce  elaborate  picture  effects.  For 
this  reason  it  is  often  best  to  represent  an  object  by  as  few  lines 
as  possible  if  in  doing  so  clearness  is  not  sacrificed.  Such  abridged 
methods  of  representing  forms  and  constructions  on  a  drawing 
are  termed  "  conventions  "  or  "  conventional  methods  "  and  are 
universally  used  to  represent  details  that  are  of  frequent  occur- 
rence, such  as  screws,  bolts,  threads,  etc. 

Conventional  methods  may  be  used  in  several  ways,  for  ex- 
ample, as  a  drawing  which  approximates  the  form  of  the  object 
being  represented;  cross-sectioning,  shown  in  color  or  by  lines 
which  symbolically  represent  the  materials ;  methods  of  represent- 
ing the  planes  in  which  an  object  is  assumed  to  be  cut;  the  path 
and  the  direction  of  motion  of  a  moving  point;  shop  operations, 
such  as  the  finish  of  surfaces,  etc.  Unfortunately  no  list  of 
conventions  can  be  universally  adopted,  and  upon  entering  the 
employ  of  a  company  the  draftsman  must  study  and  adhere 
to  their  particular  system.  Fig.  65,  page  88,  illustrates  common 
conventions,  some  of  which  are  used  in  this  course. 

Group  A,  Fig.  65,  shows  the  following  conventions: 

1.  Method  of  representing  a  shaft  of  circular  section  so  that 
space  can  be  saved  on  the  drawing.     This  method  of  repre- 
senting an  object,  as  if  a  portion  were  omitted,  cannot  be  used 
unless  the  form  of  the  portion  omitted  is  exactly  the  same  as 
the  part  shown.     Thus,  that  portion  of  a  shaft  with  a  keyway 
could  not  be  omitted  in  any  way  that  would  leave  any  infor- 
mation as  to  the  dimensions  and  location  of  the  keyway  lacking. 

2.  Method  of  representing  a  bearing.    Note  that  the  distance 
between  bearings  is  given  from  the  center  line  of  one  to  the 
center  line  of  the  other. 

3.  Method  of  representing  the  broken  end  of  a  timber  viewed 
from  the  side,  also  method  of  showing  cross  section  of  timber. 

Group  B  shows  the  following  conventions: 

i.  Method  of  representing  a  long  hollow  part  and  contracting 
the  drawing  lengthwise.  The  break  differs  from  that  of  the 
shaft  in  that  the  proportional  thickness  of  the  shell  is  shown. 


88 


ELEMENTS   OF  DRAWING 


u 


>i  I 

vj 


s 


BH-o 


MECHANICAL  DRAWING  AND  DRAFTING  ROOM  PRACTICE       89 

2.  Method  of  dimensioning  a  series  of  holes  equally  spaced 
around  a  circle.  Note  that  the  holes  are  spaced  each  side  of 
the  vertical  and  horizontal  center  lines,  and  not  on  these  center 
lines. 

Group  C  shows  conventional  uses  of  broken  or  dashed  lines 

which  are  distinct  and  must  not  be  confused  with  the  conven- 
tional method  of  representing  the  invisible  lines  of  an  object. 
See  page  76,  §  54. 

(a)  Shows  a  method  of  representing  a  moving  arm  when  in 
its  extreme  positions,  one  position  of  the  arm  being  represented 
by  full  lines,  the  other  by  dashed  lines. 

(b)  Shows  a  lever  in  its  central  position   and  the  outline 
of  the  lever  is  shown  by  broken  lines  in  each  of  its  extreme 
positions.     In  designing  and  in  bringing  out  certain  information 
clearly  it  is  often  best  to  represent  a  part  in  several  positions. 
In  checking  the  drawing  of  an  assembly  of  parts  this  method  is 
effective  in  making  sure  that  parts  which  change  position  do  not 
interfere  at  any  time  during  a  complete  cycle. 

(c)  This  shows  the  conventional  method  of  representing  a  part 
not  completely  drawn,  and  which  is  adjacent  to  the  part  drawn. 

Group  D  shows  the  conventional  methods  of  representing 
screw  threads. 

(a)  Shows  the  conventional  method  representing  the  visible 
and  invisible  V  threads.    In  each  case  the  threads  begin  and 
end  with  the  short  line,  and  in  the  invisible  or  dashed  threads  the 
dashes  of  one  line  are  opposite  the  spaces  of  the  adjacent  lines. 
The  short  lines  represent  the  bottom  line  of  the  V  and  should 
be  of  equal  length;   all  long  lines  representing  the  top  line  of 
the  V  should  be  drawn  to  meet  the  side  lines.     Note  that  the 
short  lines  in  the  visible  thread  are  about  twice  the  weight  of 
the  long  lines. 

(b)  Shows  the  conventional  Square  Thread. 

(c)  Shows  the  conventional  National  Acme  Thread. 

Where  a  part  is  threaded  for  some  length  it  is  customary  to 
show  only  a  few  threads  at  the  beginning  and  at  the  end  of  the 
threaded  portion,  thus  saving  time  without  sacrificing  clearness. 
The  threaded  portion  can  be  represented  to  scale  or  may  be 


go  ELEMENTS  OF  DRAWING 

shown  broken,  as  in  the  case  of  a  shaft,  etc.    See  Group  A-i, 
§  59,  page  87. 

Group  E  shows  the  conventional  method  of  representing  a 
drilled  hole,  a  "  tapped  "  or  threaded  hole. 

1.  If  the  hole  is  comparatively  small  a  note  usually  states  the 
size  and  the  fact  that  the  hole  is  drilled  and  a  leader  is  drawn 
from  the  note  to  the  place  where  it  applies. 

2.  If  the  hole  is  to  be  tapped  a  note  stating  the  size  of  drill 
to  be  used,  depth  of  hole,  number  of  threads  per  inch  and  the 
form  of  thread  is  printed  and -a  leader  run  to  the  place  where  the 
note  applies. 

Thus,  a  note  written  H"Drl  X  f "  X  16  U.  S.  tap  would 
indicate  that  the  hole  is  to  be  f "  deep  and  the  standard  tap  to 
give  1 6  U.  S.  threads  per  inch  is  to  be  used. 

Group  F  shows  conventional  lines  as  ordinarily  used  in  draw- 
ing. This  subject  is  taken  up  on  page  76,  §  54. 

Group  G    shows  the  method  of  giving  reference  numbers. 

This  subject  is  taken  up  on  page  104,  §  69. 

Group  H  shows  the  usual  method  of  indicating  a  cross  sec- 
tion of  structural  sheet  steel,  also  steel  shapes,  such  as  boiler 
plate.  Instead  of  section  lines  being  used,  the  cut  surface  is 
made  solid  black.  Note  that  in  the  case  of  several  pieces  being 
bolted  or  riveted  together,  they  are  shown  slightly  separated, 
since  this  adds  to  the  clearness  of  the  drawing. 

60.  Drawing  to  Scale.  Usually  in  making  a  drawing  the 
object  can  not  or  need  not  be  represented  actual  size,  and  in 
order  to  get  the  drawing  on  a  piece  of  paper  of  convenient 
dimensions,  it  must  be  made  "to  scale,"  that  is,  the  actual  meas- 
urements on  the  drawing  must  bear  some  fixed  ratio  to  the  cor- 
responding measurements  on  the  object.  The  method  of  making 
a  scale  to  such  a  ratio  is  to  choose  an  arbitrary  distance  and  let 
that  distance  represent  one  foot.  This  distance  which  represents 
one  foot  is  then  divided  into  twelve  equal  divisions,  each  of 
which  therefore  represents  one  inch.  One  of  the  twelve  divisions 
is  then  divided  into  halves,  quarters,  eighths,  etc.  (see  Fig.  31, 
page  30),  to  represent  one-half  inch,  one-quarter  inch,  and  so 


MECHANICAL  DRAWING  AND  DRAFTING  ROOM  PRACTICE     91 

on,  until  such  subdivisions  become  too  small  to  be  conveniently 
read.  To  illustrate,  suppose  a  drawing  is  to  be  made  one-fourth 
size.  To  compute  the  length  of  every  line  on  the  drawing  would 
be  a  slow  and  tedious  process,  and  would  require  that  every 
dimension  on  the  object  be  divided  by  4  to  get  the  corresponding 
dimension  on  the  drawing.  To  overcome  the  necessity  of  making 
such  computations,  imagine  an  ordinary  foot  rule  uniformly 
compressed  until  exactly  one-fourth  its  original  length.  It  would 
then  be  only  three  inches  long  but  marked  "  twelve,"  and  the 
divisions  marked  "one  inch"  would  actually  be  one-quarter  of 
an  inch  long,  those  marked  " one-half  inch"  would  actually  be 
one-eighth,  etc.  That  is,  all  the  dimensions  would  be  reduced 
to  one-quarter  size  and  any  desired  dimension,  such  as  5!  or  gf , 
etc.,  could  be  marked  off  or  read  directly  upon  the  drawing 
(which  is  one-quarter  size)  with  this  compressed  rule  and  no 
computations  whatever  would  be  necessary. 


SCALES   IN   COMMON   USE 

Actual  Measurement  on 
Drawing. 

Actual  Measurement  on  Object 
Represented. 

Size  of  Drawing  Compared  with 
Actual  Size  of  Object  Represented. 

|  inch 

One  foot 

g^th  size  (o.oio) 

\  inch 

One  foot 

t'ffth  size  (0.021) 

|  inch  f 

One  foot 

3*2  nd  size  (0.031) 

£  inch 

One  foot 

2*5  th  size  (0.042) 

f  inch  f 

One  foot 

i^th  size  (0.063) 

i  inch 

One  foot 

t^th  size  (0.083) 

i£  inches  * 

One  foot 

|th  size  (0.125) 

3  inches  * 

One  foot 

£th  size  (0.250) 

4  inches  f 

One  foot 

£rd  size  (0.3330) 

6  inches  * 

One  foot 

%  size  (0.500) 

*  Desirable  scale  for  ordinary  use. 


f  Rarely  used. 


The  above  table  should  be  thoroughly  understood  as  beginners 
are  often  misled  by  the  way  the  instrument  is  marked. 

For  example,  the  "  J"  marked  on  the  instrument  does  not  indi- 
cate that  this  scale  is  for  making  a  drawing  \  size,  but  that  J  inch 


92  ELEMENTS  OF  DRAWING 

has  been  divided  to  represent  some  convenient  division  of  inches 
in  one  foot.  This  scale  of  J  inch  to  the  foot  is  12"  -i-  J"  =  ^ 
full  size,  while  the  J  size  would  be  12"  X  J  =  3'',  or  a  scale  of  3" 
to  the  foot.  Another  fact  to  remember  is  that  dimension 
numbers  which  the  draftsman  prints  on  the  drawing  are  the 
actual  dimensions  as  measured  on  the  object  represented,  and 
not  the  distance  obtained  by  measurement  on  the  drawing  with 
the  ordinary  foot  rule  unless  the  drawing  happens  to  be  full  size. 

The  scales  most  used  in  practice  are  full  size,  or  12  inches 
equals  i  foot;  one-half  size,  or  6  inches  equals  i  foot;  one-fourth 
size,  or  3  inches  equals  i  foot,  and  one-eighth  size,  or  ij  inches 
equals  i  foot.  If  an  object  is  very  small  the  scale  of  the  draw- 
ing may  be  increased  in  order  to  make  a  satisfactory  drawing. 
For  example,  twice  size  would  mean  12  inches  on  the  drawing 
represents  6  inches  on  the  object.  It  is  often  useful  to  be  able 
to  read  these  scales  directly  from  the  foot  rule  and  not  be  depend- 
ent upon  the  special  graduation.  This  is  easily  done  by  remem- 
bering that  for  a  scale  of  6  inches  to  the  foot,  i  inch  will 
be  represented  on  the  scale  by  \  inch,  and  reading  each  \  inch  as 
i  inch,  the  subdivisions  of  the  foot  rule  would  read  as  follows: 
J"  on  the  drawing  .=  |"  on  the  object,  f "  =  J",  TV"  =  i",  etc. 

For  3  inches  to  the  foot,  or  J  size,  i  inch  is  represented  by 
J  inch,  and  the  subdivisions  would  be  read  thus:  J"  =  \ ", 

1    *   —  i"     r*f"r* 

TS      "~  4    i   eu" 

For  ij  inches  to  the  foot,  or  f  size,  i  inch  is  represented  by 
inch,  and  the  subdivisions  are  read  thus:  tV'  =  %",  sV"  =  J",  etc. 

u  ^i  Sometimes  an  unusual 
scale  is  required,  such  as  a 
shrink  rule  for  pattern 
makers.  To  construct  such 
a  scale  or  rule,  secure  a 
Fig.  66. -shrink  Rule.  standard  twelve-inch  rule 

and  the  blank  rule  that  is  to  represent  twelve  inches  on  the  new 
scale,  as  shown  in  Fig.  66.  Make  a  ruling  gauge,  G,  of  thin  sheet 
metal,  with  a  guide  flange  turned  down  to  bear  against  the 
outer  edge  of  the  blank.  Slide  the  gauge  along  the  blank  and 
mark  the  graduations  as  the  upper  edge  of  the  gauge  coincides 
with  the  standard  graduations. 


MECHANICAL  DRAWING  AND  DRAFTING  ROOM  PRACTICE     93 


61.  Choice  of  Scale  in  Drawing.  The  best  scales  to  use  in 
making  shop  drawings  are  full  size,  half  size,  three  inches  to  the 
foot,  and  one  and  one-half  inches  to  the  foot.  The  one  used 
depends  on  the  relative  proportion  of  the  size  of  the  object 
and  the  size  of  the  drawing  desired.  The  scale  of  a  drawing 
should  not  be  so  small  that  all  dimensions  and  information 
cannot  be  clearly  given.  After  the  scale  of  a  drawing  has  been 
decided  upon,  it  must  be  rigidly  adhered  to  throughout  the 
construction  of  the  views  of  a  single  part,  but  different  parts 
may  be  drawn  to  different  scales  if  there  is  any  advantage  to 
be  gained  in  so  doing. 

To  illustrate  how  to  determine  the  largest  scale  that  can  be 
used  for  any  particular  drawing,  suppose  a  drawing  of  the  Lathe 
Leg  (see  page  122,  Fig.  84) 
is  to  be  made  on  a  stand- 


E 

CO 


ard  i2"Xi8"  sheet  and 
is  to  consist  of  three  views. 
A  rough  sketch  as  shown  in 
Fig.  67  is  made  to  some 
scale,  and  the  size  of  the 
rectangle  required  to  in- 
close the  necessary  views, 
when  grouped  in  their 
proper  relation  to  one  an- 
other, is  determined.  This 
rectangle  measures  42"  by 
36",  and  therefore  if 
drawn  one-half  size  it 

WOUld  be   (£  Of  42  =  21    by  Fi*-  67-  —  Determining  the  Scale. 

\  of  36  =  1 8)  21 "  by  1 8",  and  could  not  be  drawn  on  the  sheet 
which  has  a  working  space  of  only  16"  by  n"  (see  page  106, 
Fig.  73).  The  largest  scale  possible,  if  the  part  is  represented 
vertically  on  the  sheet,  will  next  be  determined.  Dividing  n 
by  42"  gives  approximately  0.26,  and,  referring  to  §  60,  page  91, 
it  is  seen  that  the  nearest  desirable  scale  corresponding  to  0.26 
is  J  size,  or  3"  =  i  foot.  This  scale  is  therefore  adopted, 
the  drawing  is  arranged  vertically  on  the  sheet,  and  the  balance 
of  the  space  is  available  for  other  purposes. 


94  ELEMENTS  OF  DRAWING 

When  it  is  desired  to  represent  a  number  of  parts  on  a  single 
sheet  of  fixed  size,  each  part  should  be  handled  as  described 
above.  After  the  scale  has  been  decided  on,  the  rectangles 
should  be  laid  out  very  lightly  on  the  sheet  and  arranged  sym- 
metrically before  beginning  the  actual  work  of  drawing,  care 
being  taken  that  views  are  separated  by  sufficient  space  to  prop- 
erly allow  for  all  dimensions. 

62.  Dimensioning  Working  Drawings.  The  dimensions  are 
the  most  important  feature  of  the  drawing,  and  so  far  as  the 
workman  is  concerned  the  drawing  serves  only  to  show  where 
the  dimensions  apply. 

To  be  of  use  the  dimensioning  must  be  done  systematically, 
and  with  the  needs  of  those  who  will  use  the  drawing  constantly 
in  mind.  The  proper  dimensions  are  determined  by  considering 
the  processes  the  material  must  undergo  in  the  making  of  the 
part.  In  considering  such  processes  the  methods  "and  available 
tools  of  the  different  departments  of  the  shop  through  which 
the  part  will  pass  to  reach  the  finished  state  must  be  kept  in 
mind,  and  those  dimensions  given  which  the  workmen  will 
require. 

A  drawing  has  been  completely  dimensioned  when  it  has  all 
information  necessary  for  getting  out  stock,  making  patterns 
and  cores,  machining,  erecting,  etc.,  the  information  being  in 
such  shape  that  no  workman  will  be  required  to  make  a  compu- 
tation to  get  a  necessary  dimension,  or  to  seek  information  of 
any  kind  beyond  that  recorded  on  the  drawing  or  specifications. 

The  ability  to  dimension  a  drawing  satisfactorily  comes  from 
experience  and  a  thorough  knowledge  of  the  shop  processes  used 
in  making  each  part.  A  few  general  requirements,  however, 
can  be  given,  and  these  should  be  carefully  studied  by  the 
beginner  before  attempting  to  dimension  a  drawing. 

The  dimensions  on  a  drawing  must  be  accurate,  useful,  clear, 
and  complete.  If  the  dimensioning  is  inaccurate,  no  degree  of 
perfection  otherwise  can  redeem  the  drawing;  it  is  worse  than 
useless,  for  when  the  part  the  drawing  represents  is  made  it  will 
be  wrong,  and  the  labor  and,  depending  on  the  magnitude  of 
the  error,  material  will  be  totally  or  partially  lost. 


MECHANICAL  DRAWING  AND  DRAFTING  ROOM  PRACTICE     95 

To  lessen  chances  of  making  an  error,  check  computed  dimen- 
sions by  scaling  and  scaled  dimensions  by  computation,  and  if 
the  two  do  not  agree  determine  which  is  wrong.  Always  bear 
in  mind  that  the  dimension  figures  on  a  drawing  represent  the 
actual  measurements  on  the  object,  and  not  the  measurements 
on  the  drawing,  so  that  in  case  the  "  scaled"  dimensions  and  the 
calculated  dimensions  fail  to  agree,  the  workman  will  assume  that 
the  figures  are  correct  and  make  the  part  accordingly. 

If  a  dimension  is  not  to  scale,  however,  indicate  the  fact  in 
some  manner.  This  is  sometimes  done  by  underlining  these 
figures  which  are  not  to  scale. 

Place  arrowheads  so  no  mistake  can  be  made  as  to  where  the 
dimension  applies.  There  must  never  be  the  least  doubt  in 
this  regard,  and  the  dimension  line  must  always  be  drawn  far 
enough  from  other  lines  to  avoid  confusion.  The  dimension 
numbers  must  be  perfectly  plain  and  placed  as  near  the  center 
of  the  dimension  line  as  practicable,  and  they  should  read  from 
the  bottom  or  right-hand  side  of  the  drawing.  Never  place  di- 
mension numbers  on  center  lines  and  never  draw  a  line  of  any 
kind  through  such  numbers. 

The  numbers  expressing  a  dimension  should  be  so  selected 
that  they  can  be  conveniently  used  by  the  workmen  —  feet,  inches, 
fractions,  or  decimals,  as  the  case  may  be.  Because  of  the 
general  use  made  of  the  two-foot  rule,  dimension  figures  up  to 
24  inches  should  be  expressed  in  inches;  from  and  including  24 
inches  they  should  be  expressed  in  feet  and  inches. 

To  avoid  chance  of  mistakes  the  abbreviation  Ft.  should  be 
written  after  the  number  of  feet,  and  the  double  accent  mark 
used  to  indicate  inches.  The  numbers  representing  feet  and 
representing  inches  are  separated  by  a  dash  one-eighth  of  an 
inch  long,  thus  18  Ft.  -7". 

In  some  classes  of  work,  such  as  locomotive  work,  dimensions 
are  often  given  in  inches  only. 

Judgment  must  be  used  in  the  degree  of  refinement  called  for  by  the 
dimension.  Rough  castings,  even  if  small,  cannot  be  measured 
to  one-sixteenth  of  an  inch  accurately,  and  therefore  it  is  useless 
to  give  a  precise  measurement  between  a  finished  surface  and 
the  end  of  a  casting,  while  in  the  case  of  such  work  as  a  force  fit 


96  ELEMENTS  OF  DRAWING 

the  dimension  may  be  given  to  several  decimal  places,  the  vari- 
ation allowable  from  the  given  figure  being  indicated  in  the 
following  manner:  3- 128^°'°°*, —  meaning  that  a  variation  of 
0.005  above  or  below  3.128  is  permissible. 

Where  dimensions  on  the  drawing  indicate  the  final  dimen- 
sions of  the  part  when  complete,  no  allowances  are  made  by 
the  draftsman  for  shrinkage  of  castings,  finishing,  etc.,  as  this  is 
usually  taken  care  of  in  the  shop. 

The  over^alLdimensions  are  so  frequently  useful  in  estimating, 
getting  out  stock,  etc.,  that  they  should  always  be  given.  Place 
over-all  dimensions  outside  of  subdimensions,  and  in  cases  where 
dimensions  are  grouped  in  parallel  lines  the  shortest  dimension 
should  be  inside,  the  longest  outside,  and  all  others  so  arranged 
that  dimension  lines  do  not  cross. 

Always  check  over-all  dimensions  carefully  to  see  that  they 
agree  with  the  sum  of  the  dimensions  which  go  to  make  them  up. 
Do  not  rely  upon  scaling  alone  in  adding  up  a  line  of  subdi- 
mensions to  determine  an  over-all  dimension,  because  if  the 
drawing  is  slightly  out  of  scale  the  result  will  be  wrong. 

If  a  subdivided  dimension  is  between  a  finished  surface  and 
the  end  of  a  casting,  the  last  subdivided  dimension  should  be 
omitted  and  an  over-all  dimension  given. 

The  inexperienced  draftsman  will  often  give  dimensions  on 
a  drawing  which  it  is  impossible  for  the  workman  to  use  in 
making  the  part.  For  this  reason  the  dimensions  placed  on  a 
drawing  in  a  haphazard  way,  even  if  accurate,  are  very  often 
worse  than  useless.  All-  measurements  possible  should  be  from 
center  lines  that  are  convenient  for  the  workman  to  locate  on  the 
object  or  from  finished  surfaces.  Give  the  distance  between 
centers  of  important  parts,  and  if  the  object  is  symmet- 
rical, give  the  distance  of  these  centers  from  the  main  center 
line. 

Do  not  repeat  dimensions  unnecessarily  as  this  increases  the 
possibility  of  error.  Where  it  is  necessary  to  repeat  dimensions 
an  error  is  more  likely  to  be  discovered  if  the  dimensions  are 
placed  in  corresponding  positions  on  the  different  views. 

Similar  parts  should  be  similarly  dimensioned  and  dimensions 
which  are  related  should  be  kept  near  one  another. 


MECHANICAL  DRAWING  AND  DRAFTING  ROOM  PRACTICE      97 

Do  not  crowd  all  dimensions  on  a  single  view,  but  distribute 
them  to  avoid  confusion. 

Dimensions  should  not  be  crowded  into  limits  inadequate  to 
receive  them,  and  if  the  space  is  too  small  for  the  figures,  they 
may  be  placed  outside,  with  or  without  a  leader  —  that  is,  a 
line  drawn  to  indicate  where  a  note  or  dimension  applies  (see 
Fig.  88,  page  125). 

If  the  space  between  reference  lines  is  too  small  to  receive  well- 
formed  arrowheads,  the  arrowheads  may  be  reversed  and  placed 
outside  of  the  space  to  be  dimensioned,  see  Fig.  82,  page  118. 
When  a  dimension  falls  on  a  sectioned  area,  the  section  lining 
is  omitted  at  the  place  where  the  dimension  numbers  are  given. 

Where  a  complete  circle  is  shown  on  the  drawing,  such  as 
a  bored  hole  or  turned  piece,  give  the  diameter.  Cored  holes 
are  dimensioned  by  giving  the  diameter  and  stating  that  they 
are  to  be  cored;  thus,  |"core.  Fillets  and  rounded  corners  are 
given  by  their  radii.  In  giving  the  radius  of  a  circle,  R  or  Rad. 
is  written  after  the  dimension  figures,  and  an  arrowhead  is 
placed  at  the  arc  but  not  at  the  center.  Threaded  pieces  and 
tapped  holes  are  dimensioned  by  giving  the  diameter  and  num- 
ber of  threads  per  inch;  thus,  i"-i3  thd.,  or  |"-I3  tap. 

Dimensions  of  angles  should  be  given  in  degrees  and  minutes 
or  by  coordinates  from  a  reference  line,  depending  on  how  they 
are  to  be  used.  Tapers  should  be  stated  per  foot  of  length 
and  in  the  case  of  conical  surfaces  should  be  given  as  taper  on 
the  diameter. 

63.  Notes  on  a  Drawing.  Lengthy  notes  should  not  be  re- 
quired on  a  drawing  to  make  it  clear,  but  there  are  times  when 
the  art  of  drawing  fails  in  its  purpose  and  a  brief  note  carefully 
worded  saves  the  workman  much  uncertainty.  In  such  cases 
an  explicit  note  of  instruction  is  not  only  permissible  but  abso- 
lutely essential.  When  possible,  notes  should  be  placed  in  hori- 
zontal lines  and  very  close  to  the  part  to  which  they  refer,  in  order 
that  they  may  be  quickly  read  and  easily  understood.  All  notes 
should  consist  of  short,  explicit  and  concise  sentences,  should 
leave  no  doubt  as  to  their  exact  meaning,  and  should  read  from 
the  bottom  or  the  right-hand  side  of  the  drawing. 


98  ELEMENTS  OF  DRAWING 

State  all  special  directions  and  instructions  pertaining  to 
making,  painting,  shipping,  erecting,  etc.,  in  properly  worded 
notes.  No  lettering  of  notes  should  be  attempted  on  the  draw- 
ing without  first  ruling  very  light  guide  lines  to  insure  an  even 
height  and  slope  of  letters.  Guide  lines  should  be  drawn  very 
lightly  and  erased  after  the  note  is  completed.  Retrace  any 
letters  made  dim  by  erasing.  All  notes  on  drawings  in  this 
course  must  be  lettered  in  the  standard  Gothic  capitals,  unless 
otherwise  stated.  The  letters  must  be  ?V  high.  Figures  in  a 
note  should  be  made  slightly  higher  than  the  letters,  say,  J"  high. 

64.  Indicating  the  Finish  of  Surfaces.     The  surfaces  of  a 
casting  or  forging  are  spoken  of  as  "  rough  "  when  in  the  condi- 
tion in  which  they  leave  the  foundry  or  mill,  and  "finished" 
when   the  piece  has  been  subjected  to   some   tool   operation. 
Some  of  the  shop  operations  for  finishing  surfaces  with  cutting 
tools  are   turning,  planing,  milling,   grinding,  reaming,  filing, 
scraping,  and  chipping;  besides   these  processes,  surfaces  are 
often  polished,  grained,  matted,  etc.,  to  produce  artistic  effects. 
It  is  necessary  to  indicate  on  the  drawing  the  kind  of  finish  a 
surface  is  to  be  given,  so  that  the  proper  department  will  attend 
to  it,  and  also  in  order  that  the  pattern  maker  or  blacksmith 
will  allow  for  the  material  that  must  be  removed  in  producing 
this  finish.     The  usual  method  of  indicating  a  finish  made  by 
machining  is  to  place  the  letter  /  across  the  edge  mew  of  the 

surface  to  be  so  finished.    (See  Fig.  68.)     If  it  is 
to  be  other  than  the  ordinary  machine  finish,  a 
note  to  that  effect  should  be  added  and  a  leader 
run  from  the  note  to  the  finish  mark.     If  all  the 
of  indicating  ordi-    surface  of  a  part  is  to  be  finished  the  several  "/" 
aZZr*"  °D     marks  are  omitted  and  the  note  "f  ALL  OVER" 
is  printed  near  the  part  number.   As  shop  methods 
and  processes  are   continually  being   changed  in  an  effort  to 
increase  production  and  reduce  the  cost  of  manufacture  the 
drawing  should  not  specify  the  process  by  which  the  finish  is 
to  be  obtained. 

65.  Use  of  Record  Forms  and  Titles.     A  complete  record 
must  be  kept  of  every  drawing,  and  most  of  this  record  should 


MECHANICAL  DRAWING  AND  DRAFTING  ROOM  PRACTICE     99 

be  on  the  drawing  itself  in  a  particular  and  invariable  space  re- 
served for  that  purpose.  That  portion  of  the  record  which  is 
placed  on  the  drawing  should  be  systematically  tabulated  accord- 
ing to  a  fixed  form  and  should  embrace  at  least  the  following  items: 

(i)  An  appropriate  title  which  will  adequately  describe  the  con- 
tents of  the  drawing. 

•  (2)  The  name  and  address  of  the  firm  for  which  the  drawing 
is  made. 

(3)  The  title  and  names  or  initials  of  those  who  are  responsible 
for  the  finished  drawing;  this  includes  at  least  the  checker  and, 
the  approving  engineer. 

(4)  The  drawing  number  and  a  "  part  number  "  where  necessary- 

(5)  A  record  of  all  changes  made  in  the  drawing  to  adjust  it  to* 
meet  conditions  other  than  those  for  which  it  was  originally  intended^ 

(6)  The  date  the  drawing  is  officially  adopted. 

(7)  The  size  of  the  drawing  should  be  indicated  in  some  manner 
so  that  it  can  be  properly  and  systematically  filed. 

Besides  the  above  information  some  companies  insist  that  the 
drawing  bear  the  name  and  initial  of  all  those  responsible  for  it 
in  any  way.  If  this  burdens  the  drawing  with  information  use- 
ful in  the  drawing  department  only,  the  complete  history  of  the 
drawing  can  be  recorded  on  cards  or  in  a  special  book  reserved 
for  that  purpose.  Also  the  machine  or  apparatus  for  which  a 
part  is  usually  first  designed  is  recorded  and  some  scheme  is 
adopted  such  that  if  a  part  is  used  on  several  different  machines 
the  fact  is  recorded  in  such  a  manner  that  unnecessary  dupli- 
cation of  patterns  or  uncertainty  as  to  the  number  of  pieces  to 
be  kept  in  stock  is  avoided. 

It  is  very  common  practice  to  indicate  the  "  scale  "  to  which 
the  parts  represented  on  a  drawing  have  been  made,  but  the 
value  of  this  practice  is  questionable,  as  there  is  a  rule  almost 
universally  applied  that  "  the  workman  must  not  scale  a  draw- 
ing to  obtain  a  dimension."  Also  during  the  life  of  a  drawing 
it  frequently  happens  that  dimensions  are  changed,  but  the 
drawing  is  not  "kept  to  scale";  and  for  these  reasons  the 
11  scale "  on  a  drawing  might  be  a  temptation  to  break 
the  above  rule  and  in  addition  be  misleading. 


100  ELEMENTS  OF  DRAWING 

In  practice  many  different  systems  are  used  to  keep  a  record 
of  changes  on  a  drawing,  the  purpose  being  to  have  a  history 
of  progress  made,  and  to  be  able  to  furnish  repair  parts  for 
machines  in  service.  There  are  several  features  to  be  taken 
care  of  in  this  connection  but  it  is  not  within  the  scope  of  this 
book  to  go  beyond  pointing  out  the  necessity  of  keeping  a 
thoroughly  reliable  history  of  changes  made  during  the  life  of  a 
drawing. 

66.  The  Title-form  on  a  Drawing.  The  best  location  for  a 
title-form  is  the  lower  right-hand  corner  of  the  sheet.  This 
information  so  placed  makes  it  easy  to  handle  and  file  the 
drawing  and  particularly  tracings. 

There  is  no  accepted  standard  for  the  outline  and  dimensions 
of  a  title-form,  or  the  information  recorded,  but  each  individual 
establishment  evolves  .one  that  is  suited  to  its  own  use.  Care 
should  be  taken  in  the  final  selection  of  a  title-form  as  it  is  a 
very  important  item  in  a  drawing  room  system. 

The  title-form  shown  in  Fig.  69  represents  a  general  average, 
and  will  be  used  in  this  work  on  all  mechanical  drawings  of  the 


P3 

2 

\f 

$ 

Print  Title  Here. 

5<o 

\ 

^"MACHINE  DESIGN 

'SIBLEY  COLLEGE 

•^-'ITHACA,  NEW  YORK    '^ 

DRAWN  BY"^^ 
INSPECTED    F 

\?<b 

DATE  APR  V'D 

-JJRAWING-C  IOI 

| 

<u 

<-»  r" 

T,?"" 

**-  8 

*-  8 

Fig.  69.  —  Title-form  to  be  used  in  this  Work. 

12"  X  18"  size.  This  title-form,  while  especially  applied  to 
this  work,  follows  closely  the  one  now  used  successfully  by 
several  large  manufacturing  concerns. 

All  the  lettering  in  the  title-form  is  the  Capital  Slant  Gothic 
style.  By  using  the  method  described  on  page  69,  §49,  the 
lettering  in  the  title  can  be  more  satisfactorily  arranged  by  the 
beginner. 


MECHANICAL  DRAWING  AND  DRAFTING  ROOM  PRACTICE      IOI 


The  lettering  of  the  title  (or  name  of  the  drawing)  is  TY' 
high,  and  is  located  "  centrally  "  in  the  space  provided  for  that 
purpose  which  is  If"  X  5!". 

All  other  lettering  in  the  title-form  is  £"  high  except  the 
words  DRAWING  and  SIBLEY  COLLEGE  (or  whatever  the 
name  of  the  institution),  which  are  jYr  high. 

The  space  between  all  lines  of  lettering  in  the  title-form  is 
iV  on  the  right-hand  side  and  J"  on  the  left-hand  side. 

67.  Bill  of  Material.  A  bill  of  material  should  be  placed  on 
every  detail  drawing  to  give  the  information  required  to  make 
up  the  orders  for  the  pattern  shop,  foundry,  machine  and  forge 


^ 

-Id 


BORDER  LINE 


OF  SHEET 

Fig.  70.  —  Bill  of  Material  Form  used  in  this  Work. 

shops;  to  get  out  machine  lists,  figure  stock,  cost,  etc.  The 
form  for  tabulating  this  data  varies  with  different  companies,  as 
does  also  the  place  it  occupies  on  the  drawing.  Fig.  70  shows 
a  form  for  the  bill  of  material  that  has  proven  entirely  satisfac- 
tory under  severe  conditions  and  will  be  adopted  for  this  work. 
In  Fig.  70  the  space  if "  X  5f "  directly  in  the  corner  is  reserved 
for  the  title-form  (see  page  100,  §  66).  Unless  otherwise  stated, 
locate  the  bill  of  material  form  just  above  the  title-form,  and 
provide  at  least  as  many  -fa"  spaces  as  there  are  parts  detailed 
and  standard  parts  called  for  on  the  drawing.  In  practice 
extra  tV  spaces  are  drawn  to  provide  for  future  addition  of 
parts. 


102  ELEMENTS  OF  DRAWING 

All  lettering  in  the  bill  of  material  is  ^Y'  high?  is  of  the  slant 
Gothic  style,  and  is  preferably  all  capitals. 

The  first  column  on  the  left  contains  the  number  of  pieces 
required  to  make  one  complete  machine  (or  structure)  —  in  this 
case  one  lathe.  The  second  column  contains  information  as  to 
the  material  of  which  the  part  is  to  be  made.  The  third  column 
is  for  cross  reference  and  refers  to  patterns,  other  drawings, 
punches,  dies,  etc.,  and  conveys  some  special  information  or 
instruction  which  is  required  to  make  the  data  in  column  four 
complete.  Thus,  if  the  bill  of  material  on  one  drawing  called  for 
a  piece,  say,  a  washer,  exactly  the  same  as  had  been  previously 
detailed  on  another  drawing  for  a  different  machine,  then  column 
three  would  contain  the  word  "  punching,"  which  explains  how 
the  part  is  made,  and  in  column  four  would  be  written,"  C-iyi," 
which  would  be  the  size  and  number  of  the  drawing  on  which  the 
washer  is  detailed.  Should  a  part  require  the  use  of  a  pattern 
which  has  already  been  made  for  another  machine,  that  fact 
could  be  recorded  by  writing  in  column  three  the  abbreviation 
"  Patt."  for  pattern,  and  the  number  of  the  pattern  would  be 
printed  in  column  four.  The  fourth  column  contains  pattern 
numbers  (see  page  104,  §  70)  when  the  part  is  a  casting,  punch 
and  die  numbers  when  the  part  is  a  punching,  etc.,  and  for 
other  classes  of  work  may  be  used  as  indicated  above.  The 
fifth  column  contains  the  part  numbers.  See  page  104,  §  69. 
The  sixth  column  contains  the  name  of  the  part  and  any  other 
information  thought  necessary  to  identify  the  part. 

This  particular  form  of  a  bill  of  material  has  distinctive  and 
valuable  features  which  should  be  understood.  It  is  so  laid  out 
that  the  part  numbers,  pattern  letters,  etc.,  read  from  the  bottom 
upward;  this  is  done  in  order  that  a  new  part  number  may  be 
added  at  any  time.  Also  it  is  often  found  necessary  to  make  a 
machine  differing  very  little  from  one  already  detailed,  and  ad- 
ditional columns,  each  of  which  is  exactly  the  same  width  as 
column  one  (see  page  119,  Fig.  83),  can  be  added  to  the  left  of 
column  one  and  new  groups  made.  To  illustrate,  suppose  a 
firm  manufacturing  the  speed  lathe  should  receive  an  order 
for  a  lathe  of  the  same  general  design  as  the  standard  machine 
but  to  have  a  bed  six  inches  longer.  All  that  is  necessary  under 


MECHANICAL  DRAWING  AND  DRAFTING  ROOM  PRACTICE      103 

this  system  is  to  make  out  a  new  list  to  the  left  of  column  one 
and  call  it  group  two;  schedule  all  parts  in  this  group  as  in 
group  one  except  the  bed;  add  another  part  number  to  the  top 
of  the  bill  of  material,  and  schedule  the  longer  bed.  Then  add 
a  note  near  the  drawing  of  the  original  bed  stating  that  for 
group  2  the  bed  is  to  be  a  certain  length,  and  the  drawings 
would  be  ready  to  go  through  the  shop  on  the  new  order. 

Wherever  possible,  parts  which  fit  together  on  the  complete 
machine  should  be  recorded  in  the  bill  of  material  as  consecutive 
items,  as  this  simplifies  checking  and  erecting.  For  example,  if 
two  castings  fit  together  and  are  given  the  part  numbers  i  and 
2,  the  bolts  or  screws  for  fastening  them  together  should  be 
number  3. 

When  standard  parts  are  required,  such  as  standard  bolts, 
nuts,  washers,  screws,  etc.,  they  are  not  detailed  on  the  drawing, 
but  are  given  a  part  number,  and  this  number  is  printed  in  the 
regular  way  close  to  the  place  where  the  part  is  to  fit,  and  an 
arrow  from  the  circle  points  to  the  exact  place  it  is  used.  This 
part  number  is  also  printed  in  the  bill  of  material. 

The  name  of  the  material  is  usually  abbreviated  in  the  bill 
of  material,  some  of  the  more  common  abbreviations  being: 
Cast  Iron,  C.I.;  Wrought  Iron,  W.I.;  Malleable  Iron,  Mal.L; 
Machine  Steel,  M.S.;  Cold  Rolled  Steel,  C.R.S.;  Cast  Steel,  C.S.; 
Steel  Forging,  S.  Forg.;  Steel  Tubing,  S.  Tube.;  Brass,  B.; 
Bronze,  Bz.;  Phosphor  Bronze,  Ph.  Bz.;  Copper,  Cop.;  Babbitt, 
Bbt. ;  Fiber,  Fbr.  Where  it  is  necessary  to  use  a  material  of  an 
exact  analysis  or  specification  it  is  best  to  call  for  it  by  a  number 
(see  page  81,  §  55). 

68.   Numbering  and  Indicating  the   Size  of  Drawings.     In 

order  to  be  easily  classified,  recorded,  filed,  and  referred  to,  draw- 
ings should  be  given  a  number.  There  is  no  universally  accepted 
system  for  numbering  drawings,  and  the  method  followed  by 
each  particular  firm  depends  largely  on  the  magnitude  and 
variety  of  its  business. 

It  is  also  necessary  to  have  some  simple  and  effective  means 
of  indicating  the  size  of  a  drawing,  as  those  of  different  sizes  are 
usually  filed  in  different  cases  or  drawers. 


104  ELEMENTS  OF  DRAWING 

In  order  to  secure  uniformity,  and  also  to  save  waste  in  cutting 
paper  and  tracing  cloth,  four  standard  sizes  of  drawings  have 
been  adopted  in  most  commercial  drawing  rooms,  and  these 
sizes  are  indicated  on  the  drawing  by  a  capital  letter  used  in 
connection  with  the  number  of  the  drawing.  For  instance,  the 
sizes  indicated  by  the  letter  might  be  as  follows  :  The  letter  A 
to  indicate  a  drawing  24"  X  36";  B,  a  drawing  18"  X  24";  C,  a 
drawing  12"  X  18";  D,  a  drawing  9"  X  12". 

In  this  course  all  exercises  in  mechanical  drawing  are  worked 
on  paper  12"  X  18",  and  consequently  their  size  is  indicated  by 
the  capital  letter  C,  and  the  block  of  numbers  reserved  for 
this  work  begins  with  101  and  extends  to  200.  Thus  drawing 
C-I03  would  be  12"  X  18"  in  size,  and  the  third  consecutive 
mechanical  drawing  made  in  the  course. 

69.  Part  Numbers  on  a  Drawing.  In  order  to  refer  to  any 
individual  part  (or  element  of  a  machine)  in  making  up  orders, 
tabulating  bills  of  material,  etc.,  each  part  detailed  on  a  drawing 
is  given  a  number  to  identify  it.  This  identifying  number  is 
termed  the  "part  number"  (or  reference  number),  and  is  printed 
near  the  views  of  the  part  and  is  inclosed  in  a  circle.  On  a 
pencil  drawing  both  number  and  circle  A 
are  double  lined,  but  these  are  drawn  $,  ^ 


solid  when  inked.     (See  Fig.  71.)     The  . 
circle  should  always  be  drawn  after        Fig.  71.  —  Layout  of  "  Part 
the  number  is  formed  and  in  such  a     Numbers  "  as  used  *  this  Work' 
position  that  the  number  appears  "  central  "  in  the  circle. 

It  sometimes  happens  that  a  single  part  will  require  more 
than  one  part  number.  As  an  example,  take  the  washer  detailed 
on  drawing  C-ioi.  Two  washers  are  required,  of  exactly  the 
same  form  and  dimensions,  but  are  made  of  different  materials. 
Therefore,  in  place  of  repeating  the  drawing  of  the  washer,  the 
one  drawing  is  given  two  numbers,  and  the  material  of  which 
each  is  made  is  called  for  at  the  proper  place  in  the  bill  of 
material. 

70.  Recording  Patterns  on  a  Drawing.  When  a  pattern  is 
required  in  order  to  produce  a  part,  the  pattern  should  be  given 


MECHANICAL  DRAWING  AND  DRAFTING  ROOM  PRACTICE      105 

a  number  so  that  it  can  be  listed,  identified  and  referred  to. 
This  riumber  is  usually  assigned  in  the  drawing  room  and  is  re- 
corded in  the  bill  of  materials.  This  will  be  explained  more 
fully  later.  When  practical  these  numbers  are  fastened  to  the 
pattern  in  raised  figures  and  letters,  and  therefore  appear  on 
the  casting.  By  this  means  a  broken  or  obsolete  part  of  a 
machine  may  be  replaced  by  simply  ordering  the  part  by  its 
number  from  the  manufacturers. 

The  method  to  be  followed  in  this  course  for  marking  pat- 
terns will  be  to  give  to  them  the  same  number  as  the  drawing  on 
which  the  part  is  first  detailed,  and  then  add  a  capital  letter  to 
identify  the  patterns  required  by  the  different  parts  detailed  on 
a  single  sheet.  The  pattern  letters  on  each  drawing  begin  with  A 
and  continue  through  the  alphabet  in  the  order  they  are  recorded 
in  the  bill  of  material.  Thus,  the  first  pattern  required  on 
drawing  158  would  be  marked  "  Patt.  I58-A";  the  second 
would  be  marked  "  Patt.  158-6,"  and  so  on  through  the  alpha- 
bet as  far  as  necessary.  It  often  occurs  that  in  a  new  machine 
some  part  requiring  a  pattern  will  be  the  same  as  the  corre- 
sponding part  of  an  old  machine.  In  such  cases  the  old  pattern 
number  must  be  given  on  the  new  drawing,  and  the  old  pattern 
used  for  the  new  machine.  For  example,  suppose  the  fourth 
pattern  required  on  drawing  136  could  be  used  for  the  first 
pattern  required  by  drawing  158.  Instead  of  numbering 
the  pattern  I58-A,  it  would  keep  its  old  number  (136-0)  and 
would  be  recorded  as  136-0  on  drawing  158.  The  lettering 
of  the  new  patterns  required  on  drawing  158  would  not  be 
affected  by  the  fact  that  one  or  more  old  patterns  are  called 
for.  In  marking  patterns,  such  letters  as  /,  0,  and  Q  should 
be  avoided,  as  they  are  easily  confused  with  numerals  of 
similar  outline. 

71.  Time  Keeping  in  Drawing.  In  practice  the  draftsman  is 
usually  required  to  keep  a  record  of  the  time  devoted  to  each 
drawing.  This  record  is  usually  kept  in  a  time  book  or  on  cards, 
and  is  of  value  in  computing  drawing-room  expenses,  as  well 
as  useful  in  determining  to  some  extent  the  value  of  the  drafts- 
man's services  to  the  company. 


io6 


ELEMENTS  OF  DRAWING 


FINISHED. 


TOTAL  HOURS. 


Fig.  72.  —  Time-keeping  Form 
used  in  this  Work. 


In  order  to  apply  the  principle  of 
time-keeping  in  this  course  and  yet 
avoid  using  the  card  system  the  form 
as  shown  in  Fig.  72  will  be  used. 
This  form  is  to  be  printed  with  the 
rubber  stamp  (provided  for  the  pur- 
pose) just  above  the  lower  border 
line,  and  to  the  left  of  the  title-form, 
unless  another  location  is  indicated. 


72.  Border  Lines.    Border  lines  are  drawn  parallel  to  and 
near  the  edges  of  the  paper  to  form  a  frame  for  the  drawing. 


EDGE  OF  PAPER- 


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EDGE  OF  PAPER'S 

Fig.  73-  —  Layout  of  Standard  Drawing  as  used  in  this  Work. 

Their  principal  object  is  to  set  off  a  margin,  which  gives  the 
drawing  a  finished  appearance,  and  to  lessen  the  chances  of  poor 
results  in  trimming  and  blue  printing.  The  border  lines  should 
be  drawn  very  close,  say,  |  inch  from  the  edge  of  the  paper,  as  this 
margin  represents  so  much  waste  space.  The  border  lines  should 
be  the  first  lines  drawn  on  a  pencil  drawing,  in  order  to  act  as  match 
lines  to  reset  the  drawing  in  case  it  has  to  be  temporarily  re- 
moved or  shifted.  The  border  lines  are  drawn  in  last  on  an  inked 
drawing  and  should  not  be  too  heavy,  say,  not  over  ^V'  wide,  the 
exact  width  depending  somewhat  on  the  size  of  the  drawing. 

Fig.  73  shows  the  layout  of  border  line  to  be  used  in  this 
work. 


MECHANICAL  DRAWING  AND  DRAFTING  ROOM  PRACTICE      107 

Having  placed  the  paper  "  square  "  on  the  board  (see  this 
page,  §73),  draw  a  very  light  horizontal  line  entirely  across 
the  paper,  |"  from  the  top  edge;  make  a  mark  on  this  line 
y  from  the  right-hand  edge  of  the  paper,  and  then  with  the 
aid  of  the  triangle,  guided  by  the  working  edge  of  the  T- 
square  blade,  draw  in  very  lightly  the  right-hand  vertical  line 
through  this  point.  Next,  lay  off  the  distance  between  the 
right  and  left  hand  border  lines  along  the  top  border  line,  and 
by  aid  of  the  T-square  and  the  triangle  draw  in  the  left-hand 
border  line.  On  this  line  lay  off  the  distance  between  the  top 
and  bottom  border  lines,  and  with  the  T-square  draw  in  the 
bottom  border  line.  Any  part  of  the  lines  extending  beyond 
the  corners  must  be  erased,  and  the  whole  border  retraced  and 
the  lines  made  clear  cut  and  of  the  desired  weight.  The  wide 
margin  on  the  left  is  to  allow  for  binding  the  sheets  of  this 
course  together.  In  practice,  however,  it  is  customary  to  have 
the  same  margin  on  all  sides. 

73.   To  Fasten  the  Paper  or  Tracing  Cloth  to  the  Board.     The 

paper  or  cloth  should  be  " square"  with  the  board;  it  should  lie 
perfectly  flat  and  smooth,  and  only  one  drawing  should  be  tacked 


Fig.  74.  —  Placing  a  Drawing  on  the  Board. 

on  the  board  at  a  time.  Place  the  paper  about  midway  between 
top  and  bottom,  and  rather  close  to  the  left-hand  edge  (i.e., 
working  edge)  of  the  drawing  board  and  insert  a  thumb  tack 
in  the  upper  left-hand  corner.  Then,  holding  the  T-square  in 
its  proper  position  with  the  left  hand,  manipulate  the  paper  or 
cloth  with  the  right  hand  until  the  upper  edge  of  the  paper  and 
the  working  edge  of  the  T-square  are  in  line.  (See  Fig.  74.) 
Smooth  the  paper  diagonally  with  the  right  hand  from  the 
upper  left-hand  to  the  lower  right-hand  corner  and  tack  this 


I08  ELEMENTS  OF  DRAWING 

corner  down.  Next,  smooth  the  paper  from  the  center  to  each 
of  the  other  two  corners  and  tack  them  down.  To  securely 
fasten  large  sheets,  it  is  usually  necessary  to  use  thumb  tacks 
along  the  edges  as  well  as  at  each  corner  of  the  sheet.  All 
thumb  tacks  should  be  so  placed  that  the  outer  edge  of  the 
head  comes  about  even  with  the  edge  of  the  drawing  paper  or 
tracing  cloth.  Also  the  thumb-tack  head  must  be  pushed  tight 
against  the  paper  so  that  the  head  will  offer  the  least  obstruc- 
tion to  the  triangles  and  T-square.  It  is  often  advisable  in 
doing  accurate  work  to  temporarily  remove  a  thumb  tack  if  the 
head  interferes  with  the  free  use  of  triangles  or  T-square,  but 
in  such  cases  the  alignment  of  the  drawing  must  not  be  dis- 
turbed. 

Stretching  or  smoothing  the  paper  or  tracing-cloth  with  soiled 
or  moist  hands  injures  the  drawing  surface. 

Unless  stated  to  the  contrary,  the  drawing  paper  for  this 
course  should  be  tacked  down  with  short  dimensions  parallel  to  the 
working  edge  of  the  drawing  board. 

74.  To  make  a  Pencil  Drawing.  Good  penciling  is  a  requi- 
site to  good  inking,  and  a  drawing  is  seldom  improved  in  inking 
if  poorly  done  in  pencil.  The  pencil  must  be  kept  well  sharp- 
ened (see  page  15,  §  14),  so  that  the  lines  drawn  will  be  clear, 
sharp,  and  of  the  proper  weight. 

The  direction  in  which  mechanically  made  lines  in  either 
pencil  or  ink  should  be  drawn  is  shown  on  page  21,  Fig.  19. 
Vertical  lines  and  all  those  lying  in  the  angle  AOC  are  ruled 
against  the  left-hand  edge  of  the  triangle  and  the  lines  in  the 
angle  COE  are  ruled  against  the  right-hand  edge. 

Center  lines  should  first  be  drawn  as  light  continuous  lines, 
and  later  be  retraced  in  their  proper  construction,  being  left 
broken  where  necessary  to  avoid  crossing  a  dimension  figure. 
Such  a  break  in  a  center  line  should  be  made  about  the  middle 
of  a  long  dash  and  should  not  immediately  precede  or  follow  a 
short  dash  of  the  line.  If  the  center  lines  are  drawn  heavy  at 
first  they  must  be  erased  at  the  places  where  they  would  cross 
dimensions,  and  if  not  gone  over  again  the  ends  next  to  where 
the  erasing  was  done  are  ragged. 


MECHANICAL  DRAWING  AND  DRAFTING  ROOM  PRACTICE     IOO/ 

Do  not  complete  each  view  separately,  but,  having  one  well 
along,  commence  the  drawing  of  others.  In  this  manner  errors 
are  more  readily  detected,  and  the  drawing  of  each  view  be- 
comes a  check  on  the  others.  All  the  views,  however,  repre- 
senting one  part  should  be  completed  before  starting  to  draw 
another  part  on  the  same  sheet. 

In  making  drawings  of  spindles,  shafts,  and  parts  where  most 
of  the  lines  are  at  right  angles  to  one  another,  measure  off  the 
horizontal  lengths  along  the  center  line,  and  through  these 
points  draw  the  vertical  lines  of  the  drawing  very  lightly  and  of 
indefinite  length.  On  these  vertical  lines  measure  the  diameters, 
and  through  these  points  draw  in  the  horizontal  lines.  These 
may  be  put  in  full  weight  at  once,  since  their  limits  are  denned 
by  the  light  vertical  lines.  Next,  that  portion  of  the  light  ver- 
tical line  which  is  needed  is  drawn  in  heavy.  All  the  lightly 
drawn  horizontal  lines  which  are  to  become  dimension  lines  are 
next  gone  over  (between  the  proper  reference  lines)  and  formed 
into  the  two  short  and  one  long  dash  construction.  These  lines 
should  be  made  of  the  proper  weight,  and  left  properly  broken 
for  their  dimension  figures.  When  all  of  the  dimension  lines 
are  on  the  drawing,  put  in  the  arrowheads  and  dimensions,  then 
letter  in  the  necessary  notes.  Do  not  print  in  the  dimension 
numbers  until  the  drawing  is  completed,  as  this  insures  greater 
accuracy.  There  should  be  a  space  of  at  least  TV'  between  a 
note  and  any  line  of  the  drawing,  including  dimension  lines  and 
figures.  In  laying  off  dimensions,  point  them  off  directly  from 
the  scale  (see  page  30,  Fig.  32),  and  do  not  transfer  them  from 
the  scale  to  the  drawing  by  use  of  the  dividers. 

Time  is  often  gained  and  the  work  is  usually  more  accurate 
if  the  drawing  is  systematically  done.  A  good  method  of  pro- 
cedure in  making  a  pencil  drawing  is  as  follows : 

1.  Draw  border  lines. 

2.  Block  out  bill  of  material  and  title  form. 

3.  Arrange  the  views   (see  page   74,   Figs.   50  and  51,  also 
page  75,  Fig.  52)  and  draw  main  center  lines. 

4.  Draw  the  main  lines  of  the  part,  using  very  light  continuous 
lines. 

5.  Complete  all  views  of  the  part. 


110  ELEMENTS  OF  DRAWING 

6.  Put  in  dimensions  and  notes. 

7.  Retrace  center  lines,  making  them  the  proper  weight  and  of 
the  characteristic  dot  and  dash  construction. 

8.  Complete  title  and  bill  of  material. 

75.  Inking  Drawings.  Before  beginning  to  ink,  thoroughly 
clean  the  drawing,  removing  all  dust,  lint,  particles  of  worn- 
off  rubber,  etc.,  and  be  exceedingly  careful  that  the  hands  and 
instruments,  especially  the  triangles  and  the  T-square,  are  clean 
and  free  from  dust,  so  that  they  will  not  soil  the  drawing. 

Examine  the  points  of  the  bow  pen,  compass,  or  ordinary 
pen  before  using  them,  to  make  sure  that  the  nibs  are  clean, 
are  of  the  same  length,  and  come  together  evenly.  Always 
shake  the  ink  bottle  well  before  using  the  ink,  since,  when  the 
bottle  stands  undisturbed  for  some  time,  the  coloring  matter 
in  the  ink  gradually  settles  to  the  bottom.  Under  such  con- 
ditions the  charge  of  ink  carried  by  the  pen  will  not  be  of  the 
same  density,  but  will  be  more  highly  colored  at  first,  and  as  the 
thinner  ink  from  above  reaches  the  drawing  surface  the  line  will 
vary  in  color;  that  is,  taking  the  case  of  black  ink,  it  will  vary 
from  a  jet  black  to  a  grayish  black  in  appearance.  When  such 
lines  are  on  tracings  it  is  impossible  to  obtain  satisfactory  blue- 
prints. After  filling  the  instrument  with  ink,  test  it  on  a  sepa- 
rate piece  of  paper  to  see  that  the  ink  is  flowing  properly  and 
that  the  width  of  the  line  is  correct.  If  the  ink  does  not  flow 
freely,  touch  the  point  of  the  pen  to  the  drawing  board,  the 
penwiper,  or  the  end  of  the  finger.  If  ink  still  does  not  flow, 

slightly  dampen  the  finger  and  touch 
it  to  the  point  of  the  pen,  or  remove 
the  dried  ink  with  a  slip  of  thin  paper 
drawn  between  the  nibs.  (See  Fig. 
75.)  As  a  last  resort,  thoroughly 

Fig.  75-  — Cleaning  the  Ruling  Pen.     '°  6      J 

clean  and  refill  the  pen.  More  un- 
satisfactory work  results  from  the  use  of  a  dirty  pen  than  from  any 
other  cause,  hence  the  nibs  of  the  pen  should  be  cleaned  each  time 
a  charge  of  ink  has  been  exhausted,  and  under  no  circumstances 
should  the  pen  be  put  away  without  having  been  first  thoroughly 
cleaned. 


MECHANICAL  DRAWING  AND  DRAFTING  ROOM  PRACTICE     III 

Before  inking  a  line,  understand  what  kind  of  a  line  it  is, 
that  is,  whether  full  or  broken,  the  purpose  of  the  line,  and 
where  it  begins  and  ends.  Start  inking  at  the  top  and  left-hand 
side,  and  work  down  and  toward  the  right,  for  in  this  way  the 
wet  ink  is  not  smeared  with  the  hand,  T-square,  or  triangles. 

In  drawing  a  line,  hold  the  pen  at  the  starting  point  for  an 
instant  until  the  ink  begins  to  flow,  and  then  move  it  along  the 
pencil  line  at  a  uniform  and  moderate  speed.  On  reaching  the 
end  of  the  line,  immediately  raise  the  pen  from  the  drawing, 
otherwise  the  ink  continues  to  flow  and  the  line  spreads  at  the 
end.  If  a  good  line  is  not  produced  at  the  first  attempt,  do  not 
push  the  pen  backward  over  the  line,  but  go  over  it  a  second  time 
in  the  proper  direction,  taking  care  not  to  widen  the  line  in 
retracing.  If  several  lines  meet  at  a  point,  allow  sufficient  time 
for  each  line  in  turn  to  dry,  and,  if  possible,  ink  from,  and  not 
toward,  the  point  of  intersection.  Since  it  is  difficult  for  a  be- 
ginner to  join  two  lines  so  that  they  appear  smooth  and  contin- 
uous, the  pen  should  hold  sufficient  ink  at  the  beginning  to  complete 
the  line.  Too  much  ink  in  the  pen  gives  a  heavier  line  than 
is  desired,  and  too  little  ink  results  in  too  light  a  line. 

Blotting  and  faulty  lines  are  two  of  the  main  sources  of  trouble 
in  inking  a  drawing.  Blotting  may  result  from  overloading  the 
pen  with  ink;  from  allowing  the  ruling  edge  to  come  in  contact 
with  a  line  before  it  is  dry;  from  lint,  particles  of  worn-off 
rubber,  or  dust  being  caught  on  the  point  of  the  pen;  from 
inclining  the  pen  toward  the  ruling  edge  so  that  ink  is  drawn 
under  the  edge  of  the  T-square  or  triangle;  from  getting  ink  on 
the  outside  of  the  nibs  in  filling  the  pen,  or  because  of  the  nibs 
being  nicked,  corroded,  or  otherwise  out  of  condition.  If  a  blot 
is  made,  absorb  the  surplus  ink  by  applying  the  corner  of  a 
blotter  to  the  top  of  the  ink  globule.  To  lay  the  blotting  paper 
directly  on  the  blot  tends  to  spread  the  ink  and  to  injure  the ' 
wet  surface. 

Faulty  lines  are  usually  of  variable  width  or  ragged  along  the 
edges.  A  line  of  variable  width  may  result  from  changing  the 
speed  at  which  the  pen  is  moved,  thus  causing  a  variable  flow 
of  ink;  and  from  varying  the  pressure  against  the  drawing 
or  ruling  edge,  thus  springing  the  blades  and  changing  the  dis- 


112  ELEMENTS  OF  DRAWING 

tance  between  the  nibs.  The  pen  point  may  encounter  lint,  dust, 
or  particles  of  worn-off  rubber  in  its  path,  thus  causing  the 
ink  to  flow  irregularly,  or  the  pen  may  be  too  full  or  not  suffi- 
ciently full  of  ink,  thus  varying  the  rate  of  ink  flow. 

A  ragged  line  may  result  from  the  pen  not  being  clean;  the 
nibs  being  so  dull  that  the  edges  of  the  line  are  broken;  both  nibs 
not  touching  the  drawing  at  the  same  time,  due  either  to  the 
blades  being  of  different  length  or  because  the  pen  is  not  held 
in  a  vertical  plane  parallel  to  the  working  edge. 

Always  allow  ink  to  become  thoroughly  dry  before  attempting  to 
erase  it. 

Drawing  ink  should  never  be  blotted  as  this  causes  the  lines 
to  appear  dim  and  blotting  on  a  tracing  destroys  the  opaque 
qualities  of  the  line  for  printing.  A  very  wide  line  should  be 
" built  up"  of  a  series  of  narrower  merging  lines  made  by  par- 
allel strokes. 

Do  not  place  the  ink  bottle  on  the  drawing  board  as  ink 

may     be     accidentally 
spilled.     The  danger  of 
overturning     may     be 
lessened  by  using  an  ink 
bottle  holder,  sev- 
eral   styles   of 
which  are  on  the 
market.    A  circu- 
lar piece  of  wood 

Fig.  76.  —  Two  Simple  Designs  of  Ink  Bottle  Holders.  r  f 

or  a  piece  of  draw- 
ing paper  cut  to  receive  the  bottle  and  hold  it  securely,  as  shown 
in  Fig.  76,  is  commonly  used. 

The  drawing,  when  not  in  use,  should  be  kept  covered  with 
an  extra  piece  of  paper  to  protect  it  from  the  dust  and  dirt. 

Never  begin  inking  a  drawing  until  it  has  been  completely 
finished  in  pencil;  and,  in  order  to  get  the  best  results  and  to 
save  time,  do  the  inking  systematically.  Opinions  differ  as  to 
the  best  order  of  inking  the  lines  on  a  drawing,  but  on  one 
point  all  are  practically  agreed,  namely,  that  curves  tangent  to  or 
joining  straight  lines  should  be  inked  first,  and  the  straight  lines 
drawn  to  the  curves. 


MECHANICAL  DRAWING  AND  DRAFTING  ROOM  PRACTICE     113 
In  inking,  a  very  good  method  of  procedure  is  as  follows: 

(1)  circles  and  arcs,  beginning  with  the  smallest; 

(2)  outlines,  beginning  with  the  lightest  and  inking  all  of  one 
weight  before  taking  up  the  next  heavier; 

(3)  hidden  surface  lines; 

(4)  extension  lines  and  dimension  lines; 

(5)  arrowheads,  dimensions  and  notes; 

(6)  cross-section  lines; 

(7)  bill  of  material  and  title; 

(8)  border  lines. 

76.  Checking  Drawings.  The  process  of  checking  consists  lit 
making  a  thorough  examination  of  every  detail  and  feature  of 
the  drawing  to  detect  any  errors  it  may  contain.  The  impor- 
tance of  efficient  checking  is  realized  when  the  ease  with  which, 
an  error  can  be  corrected  on  a  drawing  is  compared  with  the 
difficulties  and  expense  that  would  result  if  the  same  changes 
had  to  be  made  on  a  pattern,  casting,  or  forging.  Final  check- 
ing should  not  be  done  by  the  same  draftsman  who  made  the 
drawing,  as  one  does  not  readily  detect  his  own  errors.  In 
most  drawing  rooms  there  is  an  official  "  checker  "  whose  duty 
it  is  to  see  that  drawings  are  correct  in  every  detail  and  who  is 
responsible  for  the  accuracy  of  drawings  which  bear  the  official 
mark  to  indicate  they  have  been  checked.  The  checker  usually 
signs  his  initials  and  the  date  of  checking  in  the  title  form  of 
the  drawing. 

The  beginner  should  always  check  his  own  work  thoroughly  in 
order  to  gain  some  knowledge  of  checking,  as  well  as  to  detect 
any  oversights  or  errors  it  may  contain.  The  checker  must  first 
inform  himself  of  what  is  wanted,  and  then  by  methodical  steps 
examine  the  drawing  to  see  if  it  completely  fulfills  all  require- 
ments. A  good  method  of  procedure  in  checking  is  as  follows: 

1.  See  that  a  drawing  of  every  part  and  of  necessary  assem- 
blies has  been  made,  and  that  enough  views  are  correctly  drawn  to 
completely  represent  each  part. 

2.  See   that   all   scale   dimensions  agree  with  the  dimension 
figures  given  on  the   drawing,  and  that  where  a  series  of  sub- 


114  ELEMENTS  OF  DRAWING 

dimensions  make  up  an  "  over  all "  (total  dimension)  no  error  has 
been  made. 

3.  See  that  related  parts  do  not  interfere;  i.e.,  check  each  part 
with  those  parts  to  which  it  will  be  adjacent  in  the  assembled 
machine,  to   see  that  corresponding  dimensions  agree,  and  that 
proper  clearances  have  been  allowed. 

4.  See  that  dimensions  are  given  correctly,  so  that  no  com- 
puting or  scaling  will  be  necessary  when  working  with  the  draw- 
ing, and  that  notes  and  figures  are  plain  and  in  the  position  in 
which  the  reader  is  most  likely  to  look  for  them. 

5.  See  that  no  arrowheads  are  missing,  and  that  all  marks 
for  feet  and  accents  for  inches  are  correct  and  none  omitted. 

6.  Lay  out   to   scale  and   on  a  separate  sheet   the   path  of 
motion  for  moving  parts,  and  see  that  the  proper  clearances  are 
maintained  in  all  positions. 

7.  See  that  no  center  lines  are  missing,  and  that  they  are  all 
correctly  shown. 

8.  See  that  finished  surfaces  are  properly  indicated. 

9.  See  that  all  stock  material,  such  as  screws,  bolts,  rivets,  keys, 
etc.,  are  as  far  as  possible  of  standard  size. 

10.  Check  supplementary  notes  and  all  instructions  and  every 
feature  of  the  bill  of  material  and  title. 

In  addition  to  the  above  see  that  all  the  instructions  given 
in  Appendix  A,  page  175,  are  carried  out  with  reference  to 
exercises  in  this  course. 

77.  Tracing.  A  tracing  is  an  exact  copy  of  a  drawing,  made 
by  placing  transparent  cloth  (see  page  6,  §  6)  or  paper  (see 
page  6,  §  5)  over  the  drawing  and  tracing  on  this  cloth  or  paper 
lines  to  correspond  to  those  of  the  original  drawing. 

In  commercial  drafting  rooms  the  tracing  is  the  permanent 
record  of  the  drawing  and  is  used  as  a  negative  to  produce  addi- 
tional copies  of  the  drawing,  usually  by  the  blueprint  process.- 

To  make  a  tracing,  stretch  the  cloth  over  the  drawing  to  be 
traced  until  it  is  fairly  taut  and  perfectly  smooth  and  even. 
Place  a  thumb  tack  in  each  corner,  and  a  sufficient  number  around 
the  edges  to  hold  it  flat  and  well  stretched.  Before  beginning 
to  ink,  sprinkle  the  surface  of  the  cloth  with  powdered  chalk, 


MECHANICAL  DRAWING  AND  DRAFTING  ROOM  PRACTICE     115 

and  rub  lightly  with  a  soft,  clean  rag  to  overcome  the  effects  of 
any  oil  that  may  be  present;  then  brush  off  the  chalk  with  a  clean 
rag  so  that  it  will  not  pile  up  in  front  of  the  pen  when  inking. 

Greater  care  is  required  to  make  a  drawing  on  tracing  cloth 
than  on  drawing  paper,  especially  if  the  glazed  side  of  the  cloth 
is  used.  One  very  important  precaution  to  be  taken  is  10  see 
that  the  pen  is  clean,  sharp,  and  otherwise  in  good  condition. 
The  pen  should  carry  less  ink  than  when  working  on  paper, 
as  the  ink  has  a  greater  tendency  to  spread.  Take  special 
care  to  draw  the  ink  lines  exactly  over  the  pencil  lines  of 
the  drawing  being  traced.  Be  very  careful  in  inking  lines 
that  meet  or  intersect,  since  if  the  first  line  is  not  dry  (ink 
dries  slower  on  cloth  than  on  paper)  before  the  second  is 
drawn,  a  blot  will  result  at  the  point  of  meeting.  Work  only  on 
one  part  of  the  tracing  at  a  time,  and  whenever  possible  com- 
plete a  view  before  leaving  the  drawing  for  any  length  of  time, 
the  reason  for  this  being  that  moisture  in  the  air  affects  the 
cloth,  and  may  cause  it  to  warp  to  such  an  extent  that  it 
will  be  difficult  to  complete  the  view  later  on.  When  the  cloth, 
warps,  remove  thumb  tacks  and  readjust  it  to  fit  over  the 
lines  of  the  drawing  as  accurately  as  possible.  Moisture  will 
destroy  the  surface  and  transparency  of  tracing  cloth,  rendering 
it  unfit  for  printing  or  drawing.  For  this  reason  avoid  working 
on  the  cloth  with  damp  hands.  A  tracing  may  be  cleaned  with 
a  rag  or  sponge  moistened  with  benzine  or  gasoline.  Never  fold 
or  crease  tracing  cloth. 

The  same  systematic  order  given  for  inking  a  drawing  should 
be  followed  in  tracing.  See  page  no,  §  75. 

Erasures  on  a  tracing  must  be  avoided  as  far  as  possible,  but 
it  is  often  necessary  in  practice  to  make  complete  changes  of  por- 
tions of  a  view,  and  for  this  reason  the  beginner  must  learn  to 
make  erasures  without  spoiling  a  tracing.  After  the  erasure  has 
been  made,  the  smooth  surface  must  be  restored  before  again 
applying  ink.  To  smooth  the  surface,  rub  the  injured  area  with 
a  soapstone  pencil  and  polish  with  a  cloth.  See  page  18,  §  17. 

Never  use  a  knife  to  scratch  out  lines  on  tracing  cloth,  as  this 
may  cause  permanent  injury  to  the  surface  of  the  cloth.  In 
drawing  over  an  erased  area,  set  the  pen  for  a  finer  line  than  is 


Il6  ELEMENTS  OF  DRAWING 

required  and  build  the  line  up  to  the  required  width  by  making 
several  strokes. 

78.  Blueprints.     A  tracing  is  used  as  a  negative  in  reproduc- 
ing copies  of  a  drawing  by  the  blueprint  process.     Such  prints 
are   termed  "  blueprints  "  because   the  reproduced  drawing  is 
in  white  lines  on  a  blue  background.     The  prints  are  usually 
made  in  a  printing  frame,  which  is  a  device  for  holding  the  tracing 
and  the  prepared  paper  flat  and  smooth  against  a  glass  front. 
The  right  side  of  the  tracing  (i.e.,  the  side  on  which  the  drawing 
has  been  made)  is  placed  next  to  the  glass;  the  chemically  pre- 
pared side  of  the  paper  is  placed  next  to  the  tracing  and  the 
back  of  the  frame  fastened  down.      The  frame  is  then  placed  so 
that  the  glass  front  is  exposed  for  a  short  time  (the  exact  time 
depending  on  sensitiveness  of  the  blueprint  paper  and  the  in- 
tensity of  the  sunlight)  to  the  light  and  preferably  to  the  direct 
rays  of  the  sun,  after  which  the  exposed  blueprint  paper  is 
taken  out  and  washed  in  clean  water.     This  method  of  printing 
depends  more  or  less  upon  weather  conditions,  and  to  overcome 
all  uncertainty  and  avoid  delays,  printing  machines  which  print 
by  electric  light  are  used  by  many  manufacturers. 

Changes  and  alterations  on  blue  prints  may  be  made  by  several 
methods.  A  solution  of  common  soda  and  water,  or  quicklime 
and  water,  used  as  ink,  will  give  a  white  line;  but  the  best 
method  is  to  use  a  white  pencil  for  making  new  lines,  and  a  blue 
pencil  for  striking  out  white  lines. 

SET  OF   MECHANICAL  DRAWING  EXERCISES. 

79.  Drawing  C-ioi.    A  mechanical  detail  drawing  to  full-size 
scale  is  to  be  made  of  the  Lathe  Spindle  (see  Fig.  77),  the  Key 


Fig.  77- —  Perspective  of  Lathe  Spindle. 


(see  Fig.  78),  the  Fiber  and  Steel  Washers  (see  Fig.  79),  and  the 
Special  Nut  (see  Fig.  80). 

The  purpose  of  the  exercises  on  this  drawing  is  to  give  practice 
in  the  use  of  the  instruments  required  in  making  a  simple  me- 


MECHANICAL   DRAWING  AND   DRAFTING   ROOM  PRACTICE     117 


chanical  drawing;  to  illustrate  one  method  of  arranging  views, 
one  method  of  dimensioning  and  lettering,  the  use  of  the  title- 
form,  the  making  up  of  a  bill  of  material,  and  the  use  of  the 
drawing-room  system  to  be  followed  throughout  this  course. 


Fig.  78.  —  Perspective 
of  Key. 


Fig.  70.  —Perspective  of  Fibef 
or  Steel  Washer. 


Fig.  80.  —  Perspective 
of  Special  Nut.      • 


Study  carefully  the  "Introductory,"  page  71,  §  52,  and  " Detail 
Drawings,"  page  85,  §57,  before  attempting  to  draw.  Also  study 
the  location  and  learn  the  purpose  of  each  part  on  the  assembled 
machine  before  drawing  it.  (See  Frontispiece.)  Fig.  82  shows 


-^CUTTING  EDGE  OF  PAPER              -id             BORDER  LINE  O  F  DRAWING 
/                                                                                (  1                                                                                    -/-I 

0 
O 

k. 

«  / 

- 

C 

P 

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Fig.  81.  —  Layout  of  Drawing  C-ioi. 

the  complete  detail  drawings  of  these  parts,  drawn  to  a  reduced 
scale,  and  their  location  on  the  sheet  is  shown  in  Fig.  81.  As 
it  is  essential  to  be  able  to  arrange  the  views  of  a  drawing 
symmetrically  on  the  sheet,  this  is  the  only  drawing  in  which 
the  arrangement  of  views  is  given.  It  is  also  the  only  one  for 


u8 


ELEMENTS    OF   DRAWING 


MECHANICAL  DRAWING  AND  DRAFTING  ROOM  PRACTICE     119 

which  the  bill  of  material  and  title  has  been  made  out.  (See 
Fig.  83.)  These  features  should  therefore  be  noted  carefully. 

Before  starting  on  Drawing  C-ioi  read,  and  prepare  for  exam- 
ination, subjects  taken  up  in  paragraphs  as  follows: 

Introductory,   page   i,   §i,  — Drawing   Paper,  page  4,  §3. 

—  Drawing  Boards,  page  7,  §8. — Thumb  Tacks,  page  8,  §  9. 

—  T-squares,  page  8,  §  10.  —  Triangles,  page   10,  §11.— Pen- 
cil Sharpener,  page  14,  §13.— Lead  Pencils,  page  14,  §14.— 
Erasers  and  Erasures,  page  16,  §  15.  — Erasing  Shield,  page  17, 
§16.— Bow  Pencils,  page  27,  §25.— Scales,  page  29,  §27.— 
Instrument  Rag,  page  33,  §  30. — Introductory,  page  34,  §31. 


/ 

FBR: 

s 

WASHER 

/ 

M.S. 

4 

WASHER 

(? 

M.S~ 

3 

SPECIAL.  NUT 

/ 

C.R.S. 

£ 

KEY* 

1 

3.  TUBE 

1 

SPINDLE 

SPEED  LATHE  DETAILS 

MACHINE:  DESIGN 
S/BLEr  COLLEGE 

JTHACA,    NEW  yORK 

DRAWN  BY* 

INSRECrEO 

DATE  ARR'\/'C> 

DRAWING-CIO/ 

Fig.  83.  — Complete  Title  and  Bill  of  Material  for  Drawing  C-ioi. 


—  Systematic  Method  in  Lettering,  page  44,  §  36.  —  Designing 
Headings  and  Titles,  page  69,  §  49.  —  Conventional  Lines,  page 
76,  §  54.  —  Border  Lines,  page  106,  §  72.  — To  Fasten  the  Paper 
or  Tracing  Cloth  on  the  Drawing  Board,  page  107,  §  73.  —  To 
Make  a  Pencil  Drawing,  page  108,  §  74.  —  Checking  Drawings, 
page  113,  §76. 

Before  making  this  drawing  also  be  prepared  to  answer  ques- 
tions relating  to  mechanical  construction  as  follows:1  For  what 

1  Questions  of  this  nature  should  be  asked  with  reference  to  each  draw- 
ing to  be  made  in  order  that  the  beginner  will  realize  from  the  start  that 
there  is  a  relation  existing  between  drawing,  machine  design  and  shop  work. 


120  ELEMENTS  OF  DRAWING 

reason  is  the  spindle  finished  to  so  many  different  diameters? 
What  is  the  purpose  of  the  hole  through  the  spindle,  also  of  the 
Morse  taper  at  the  end  ?  Why  is  the  spindle  made  of  steel  ? 
Of  what  use  is  the  Key,  the  Special  Nut,  and  the  Washers? 

Specific  Instructions,  (a)  Tack  down  the  sheet  (see  page  107, 
§  73).  (b)  Draw  border  line  and  title-form  (see  page  106,  §  72, 
and  page  100,  §  66),  and  the  bill  of  material  form,  shown  in  Fig. 
70,  page  101.  (c)  With  the  rubber  stamp  print  in  the  blank 
form  shown  on  page  106,  Fig.  72,  just  above  the  lower  border  line 
and  to  the  left  of  the  title-form,  (d)  Write  in  with  ink  your 
NAME  (and  initials),  and  fill  in  the  DATE  BEGUN,  etc. 
(e)  The  center  line  of  the  spindle  detail  should  then  be  drawn, 
not  in  its  finished  form  and  weight,  but  as  a  very  light  contin- 
uous line  (see  page  78,  §  54).  Study  §  74,  page  108,  before  actu- 
ally starting  the  drawing.  After  the  outline  of  the  view  is 
completed,  the  center  line  can  be  made  according  to  the  conven- 
tional method,  broken  where  necessary  to  allow  for  dimensions, 
and  of  the  proper  weight.  Next,  the  outline  of  the  spindle  is 
drawn,  in  very  light  lines,  after  which  the  details  of  the  view,  also 
the  section  is  drawn.  The  portion  of  any  line  extending  beyond 
its  proper  limit  must  now  be  erased.  When  completed,  all  lines 
must  be  retraced  and  made  the  proper  weight.  (See  page  76, 
§  54.)  Next  draw  in  the  reference  lines,  being  careful  to  always 
leave  a  space  next  to  the  surface  from  which  the  line  is  extended. 
If  this  is  not  done,  it  appears  that  the  lines  have  been  drawn 
carelessly  and  that  they  extend  beyond  their  proper  limit.  Put 
in  all  dimension  lines  and  arrowheads  and  write  in  all  dimen- 
sion figures  and  notes,  always  making  them  read  from  the  bot- 
tom or  right-hand  side  of  the  drawing.  (/)  The  details  of  the 
key  and  the  washer  are  to  be  next  drawn.  Since  all  details 
on  this  drawing  are  to  be  machine  finished  all  over,  the  note 
"  /  "  ALL  OVER  is  printed  near  the  part  number  of  each  de- 
tail, (g)  Fill  in  the  DATE  FINISHED,  TOTAL  ACTUAL 
HOURS  (required  to  complete  the  work),  and  the  TITLE  of 
the  drawing.  The  Title  of  Drawing  C-ioi  is  SPEED  LATHE 
DETAILS,  (h)  Check  the  drawing  (see  page  113,  §  76),  to  see 
that  all  lines,  dimensions,  and  notes  are  correct,  that  the  bill  of 
material  is  correct,  and  that  the  part  numbers  (see  page  104,  §  69) 


MECHANICAL  DRAWING  AND  DRAFTING  ROOM  PRACTICE      121 

have  been  put  in.     (i)  Finally,   have   the  drawing  inspected, 
checked,  and  approved.     (See  page  175,  Appendix  A.) 

80.  Tracing  Drawing  C-ioi.    After  the  pencil  drawing  C-ioi 
has  been  approved  it  is  to  be  traced. 

Before  starting  to  trace  this  drawing  read,  and  prepare  for 
examination,  the  subjects  taken  up  in  paragraphs  as  follows : 

Tracing  Cloth,  page  6,  §6.  — Erasers  and  Erasures,  page 
16,  §  15. — Erasing  Shield,  page  17,  §  16. — Soapstone,  page  18, 
§  17.  — Drawing  Ink,  page  18,  §  18.  —  Ordinary  Pens,  page  18, 
§19. — Penholders,  page  20,  §20. — Ruling  Pens,  page  20, 
§21.— Bow  Pens,  page  28,  §26.  — To  Fasten  the  Paper  or 
Tracing  Cloth  on  the  Drawing  Board,  page  107,  §73.  —  Inking 
Drawings,  page  no,  §  75. —Tracing,  page  114,  §77.  — Free- 
hand Inked  Lines,  page  136,  §  96. 

Specific  Instructions.  Tack  down  the  drawing  "square"  on 
the  board  and  fasten  the  tracing  cloth  so  that  it  lies  smooth  and 
close  to  the  drawing  with  the  glazed  side  up.  (See  page  1 14,  §  77.) 

Chalk  the  tracing  cloth  and  clean  thoroughly  with  a  soft  rag. 

Ink  the  tracing  according  to  the  instruction  given  in  §  75, 
page  no. 

Remember  that  inked  lines  are  of  three  weights:  those  repre- 
senting visible  surfaces  or  outlines  are  drawn  heavy;  all  construc- 
tion lines,  reference  lines,  center  lines,  dimension  lines,  section 
lines,  etc.,  are  drawn  light;  and  lines  representing  hidden  sur- 
faces or  parts  are  drawn  medium,  that  is,  one  half  the  weight 
of  visible  lines  and  twice  the  weight  of  center  lines  and  dimen- 
sion lines. 

After  the  tracing  is  inked,  thoroughly  examine  the  work  to  see 
that  nothing  has  been  omitted,  correct  any  errors,  and  when  the 
tracing  has  been  checked,  submit  it  for  approval,  then  follow 
instructions  in  §  81  this  page. 

81.  Blueprint  of  Tracing  C-ioi.    A  blueprint  is  to  be  made 
of  Tracing  C-ioi  before  it  is  submitted  for  final   approval. 
The  purpose  of  making  the  blueprint  at  this  time  is  to  give 
the  beginner  the  benefit  of  this  experience  before  making  a 
second  tracing.    Examine  the  print  very  carefully  to  see  if  all 


122 


ELEMENTS  OF  DRAWING 


lines  are  white  and  clear,  and  in  case  some  are  not,  examine  the 
tracing  to  find  the  reason,  and  profit  by  this  knowledge  in  mak- 
ing succeeding  tracings.  All  Blueprints  must  be  trimmed  and 
filed  with  the  drawings  and  tracings. 

In  connection  with  this  exercise  read,  and  prepare  for  exami- 
nation on,  paragraphs,  as  follows: 

Tracing  paper,  page  6,  §  5.  —  Blueprint  Paper,  page  6, 
§  7.  — Drawing  Ink,  page  18,  §  18.  —  Blueprints,  page  116,  §  78. 

Having  made  a  satisfactory  blueprint,  submit  same  for  final 
approval. 

Any  tracing  spoiled  by  moisture  in  the  process  of  blueprinting 
must  be  made  over. 


82.  Drawing  €-102.     A  mechanical  drawing 
of  the  Lathe  Leg  (see  Fig.  84)  is  to  be  made 
one-quarter  size.     The  purpose  of  this  exer- 
cise is  to  introduce  the  problem  of  joining 
straight  lines  to  curves,  arranging  views  sym- 
metrically on  the  sheet,  making  a  drawing  to 
scale,  listing  patterns  in  the  Bill  of  Material, 
and  indicating  finished  surfaces ;  to  illustrate 
the  use  of  cross  sections  and  to  provide 
practice  in  drawing,  lettering,  and  dimen- 
sioning.    Fig.  85  shows  the  views,  etc. 

Before  starting  on  Drawing  C-IO2  read, 
and  prepare  for  examination,  the  subjects 
taken  up  in  paragraphs  as  follows : 

Soapstone,  page  18,  §  17.  —  Compasses, 
page  23,  §  22.— Dividers,  page  26, 
§  23. — Bow  Dividers,  page  27,  §  24. — 
The  Study  of  Lettering,  page  34,  §  32. —Projection  and  Pro- 
jected Views,  page  73,  §53.  —  Choice  of  Scale  in  Drawing, 
page  93,  §  61. — Title-form  on  a  Drawing,  page  100,  §  66. — 
Bill  of  Material,  page  101,  §  67.  —  Numbering  and  Indicating 
the  Size  of  Drawings,  page  103,  §  68.  —  Recording  Patterns  on  a 
Drawing,  page  104,  §  70. 

Before  making  this  drawing  also  be  prepared  to  answer  ques- 
tions as  follows : 


Fig.  84.  —  Perspective  of 
Lathe  Leg. 


MECHANICAL  DRAWING  AND  DRAFTING  ROOM  PRACTICE      123 


Fig-  85.  — Details  for  Drawing  C-IO2. 


124  ELEMENTS  OF  DRAWING 

State  the  reason  for  finishing  the  surfaces  as  indicated.  Ex- 
plain exactly  how  the  legs  and  bed  are  held  together.  What 
is  the  purpose  of  the  three  ££"  drilled  holes  on  the  lathe  bed? 
Explain  the  reason  for  selecting  the  cross  section  shown  on  the 
drawing. 

Specific  Instructions,  (a)  Tack  down  sheet,  (b)  Draw  bor- 
der line  and  title-form,  (c)  Stamp  printed  form  just  above 
lower  border  line  and  to  left  of  title-form,  (d)  Write,  with  ink, 
NAME  (and  initials),  fill  in  DATE  BEGUN,  etc.  (e)  Arrange 
views.  See  page  83,  §  56,  on  Number  and  Arrangement  of 
Views.  (/)  Proceed  to  make  the  drawing.  See  page  85,  §  57, 
on  Detail  Drawing,  (g)  Fill  in  TITLE,  BILL  OF  MATE- 
RIAL, DATE  FINISHED,  and  TOTAL  ACTUAL  HOURS. 
The  title  of  Drawing  C-io2  is  SPEED  LATHE  DETAILS. 
(ti)  Check  drawing,  and  submit  for  final  approval.  (See  page 
175,  Appendix  A.) 


Fig.  86.  — Perspective  of  Lathe  Bed. 

83.    Drawing    €-103.       A  mechanical   detail  drawing    (see 
Fig.  88)  is  to  be  made  of  the  Lathe  Bed  (see  Fig.  86)  and  the 
Bracket  for  the  shelf  (see  Fig.  87),  also  the 
Standard    Parts    belonging    to    the    above 
parts  are  to  be  listed  in  the  Bill  of  Material. 
Following  is  a  complete  list  of  parts  which 
are  to  be  called  for  in  the  Bill  of  Material: 
Part    #i  —  Bed. 
Part    #2  —  y  X  4"     Square-head     Cap 

Screw. 

Part  #3  — y  X  i"  Square-head  Cap  Screw. 
Part  #4  —  Bracket  for  shelf. 
Fig.  87. -Perspective  of       part  #5 _£"  x  i|"  Square-head  Cap  Screw. 

Shelf  Bracket.  •'•'•>  . 

Before  starting  this  exercise  read  and  pre- 
pare for  examination  on  paragraphs  as  follows: 


MECHANICAL  DRAWING  AND  DRAFTING  ROOM  PRACTICE      125 


FIT 

- 

T~~7~) 

tf>3 

i 

~~® 
0 

—  if 

- 

T; 

£ 

- 

tfr) 

I 

fc 

^ 

I- 
i 

> 
N 

*— 
> 

»     2 

i 
J 

j 

-T 

126  ELEMENTS  OF  DRAWING 

Introductory,  page  71,  §  52.  —  Conventional  Lines,  page  76, 
§  54.  —  Sectioning  and  Sectional  Views,  page  79,  §  55.  —  Num- 
ber and  Arrangement  of  Views,  page  83,  §  56.  —  Detail  Draw- 
ings, page  85,  §  57.  —  Indicating  the  Finish  of  Surfaces,  page 
98,  §  64.  —  Part  Numbers  on  a  Drawing,  page  104,  §  69. 

Determine  the  number  of  each  of  these  parts  required,  assign 
pattern  numbers  as  necessary,  etc. 

The  drawing  is  to  be  made  to  a  scale  of  4"  =  i  ft.,  and  the 
title  of  the  drawing  will  be  SPEED  LATHE  DETAILS.  No 
drawing  is  made  of  the  standard  parts  (see  page  103,  §  67),  but 
their  reference  numbers  must  be  properly  shown  on  the  drawing 
from  which  a  "  leader  "  must  be  run  to  the  exact  place  that  the 
standard  part  is  used  on  the  part  detailed. 

Follow  specific  instructions  given  for  preceding  drawings,  in  so 
far  as  they  apply  to  this  drawing. 

84.  Drawing  0-104.  This  drawing  represents  Bolts,  Nuts 
and  Screws,  and  is  intended  to  introduce  the  method  of  propor- 
tioning parts  by  empirical  formulas,  i.e.,  formulas  which  have  not 
been  " derived"  by  purely  theoretical  consideration;  also  it  is 
intended  to  teach  the  relative  proportions  (or  dimensions)  of 
U.  S.  (United  States)  Standard  Bolts  and  Nuts. 

This  drawing  is  further  intended  to  teach  the  relative  pro- 
portions of  the  ordinary  forms  of  screw  heads  in  common  use, 
the  conventional  method  of  representing  screw  threads  and  the 
method  of  calling  for  all  such  parts  in  a  Bill  of  Material. 

Before  taking  up  this  exercise  read  and  be  prepared  for  exam- 
ination on  paragraphs  as  follows: 

Slope  of  Letters,  page  36,  §33.  —  Conventional  Methods, 
page  87,  §  59. 

It  is  coming  to  be  more  and  more  the  common  practice  in  the 
United  States  to  use  the  U.  S.  form  of  thread,  whether  the  piece 
threaded  be  a  bolt,  nut,  screw  or  rod. 

In  the  case  of  screws  the  manufacturers  of  the  United  States 
are  gradually  adopting  the  A.  S.  M.  E.  (American  Society  of 
Mechanical  Engineers)  standard. 

Ordinarily  none  of  these  "  standard  "  parts  need  be  drawn 
out,  but  the  exercises  on  this  drawing  will  be  very  valuable  to 


MECHANICAL  DRAWING  AND  DRAFTING  ROOM  PRACTICE      127 


the  beginner  because  they  will  associate  in  the  mind  the  form  and 
proportion,  the  number  of  threads  per  inch  and  the  method  of 
calling  for  such  parts  in  the  Bill  of  Material. 

Specific  Instructions.  Ideas  as  to  this  drawing  can  be  gained 
by  reference  to  Fig.  89,  page  1 28.  Having  drawn  the  border  line 
and  the  title-form,  lay  out  and  fill  in  the  Bill  of  Material,  the 
items  being  given  below.  The  items  in  the  Bill  of  Material 
can  be  abbreviated,  but,  owing  to  the  limited  space,  it  is  even 
then  necessary  to  compress  the  lettering  which  should  be 
blocked  out  in  very  light  lines  before  being  printed  in  final 
form.  Care  must  be  taken,  however,  to  correctly  space  letters 
and  words. 

The  following  items  are  to  appear  in  the  Bill  of  Material : 


Part  .#i 
Part  #2 
Part  #3 
Part  #4 
Part  #5 
Part  #6 
Part  #7 
Part  #8 


y  X  6"  Square-head  Bolt,  Nut,  Check  Nut. 
•y  X  6"  Hexagon-head  Bolt,  Nut,  Check  Nut. 
f"  X  2y  Hexagon-head  Cap  Screw, 
f"  X  2"  Fillister-head  Cap  Screw, 
f "  X  2"  Round-head  Cap  Screw. 
y  X  1 1"  Flat-head  Cap  Screw. 
•y  X  ij"  Set  Screw. 


—  f"  X  i"  Headless  Set  Screw. 


The  following  Table  of  Threads  is  to  be  placed  exactly  above, 
and  |"  from  the  Bill  of  Material. 


Diam.  of  Bolt.  . 

i" 

4 

&' 

r 

16 

&" 

r 
13 

A' 

12 

5." 

I" 
IO 

f* 

9 

I* 

it* 

7 

i** 

if 

2" 

2|" 

3* 

Threads  per  inch 

20 

18 

14 

II 

8 

6 

5 

ti 

4 

3^ 

The  title  of  this  drawing  is  BOLTS,  NUTS,  AND  SCREWS. 

The  next  step  is  to  make  substitutions  in  the  formulas  and 
work  out  the  dimensions  of  the  bolts,  nuts,  and  screws.  These 
computations  must  be  neatly  inked  on  standard  computation 
paper,  and  the  sheets  attached  with  paper  fasteners  to  the 
drawing  when  it  is  handed  in. 

As  an  illustration  of  how  the  computations  are  to  be  arranged, 
Item  No.  7  is  worked  out  as  follows: 


128 


ELEMENTS  OF  DRAWING 


CAP  SCREW  HEAD 


FILLISTER  HEAD 


E=A;  C=2A 

DISTANCE  ACROSS  FLAT=B 
WHEN  A    <±" 

'•'  WHEN  A  >  4r 


J 


f.-.i 

E-A;     C=2. 

SET  SCRHW 


;  D-2A 


H-f 


T=D 


ROUND   HEAD 


C-jA;D=lJA 


FINISH  FOR  ENDS  OF 

BOLTS,  CAP   SCREWS 

AND    STUDS 


FINISH  FOR  ENDS  OF 
MACHINE  SCREWS 


Fig.  89.  —  "Standard"  Proportions  of  Ordinary  Nuts,  Screw  Heads,  etc. 


MECHANICAL  DRAWING  AND  DRAFTING  ROOM  PRACTICE     129 

Item  No.  7: 

y  X  iy  Set  Screw. 

E  =  A  =  y. 

c  =  2  A  =  2  x  y  =  i*. 

7~)  —3.     A    —   3.   v  i"   —  -3  " 
LJ  —  s   -n-    —  8    /\  2        ~    1'B"   • 

The  computations  for  each  item  must  be  kept  as  shown,  and 
as  many  items  should  be  placed  on  a  sheet  as  possible  without 
crowding. 

Having  computed  the  dimensions  of  all  the  parts  to  appear 
on  Drawing  0-104,  block  out  the  space  to  the  best  advantage, 
and  complete  the  drawing,  keeping  in  mind  the  following  facts: 

Conventionally  drawn  threads  begin  and  end  with  a  short  line. 
(See  page  72,  Fig.  49.) 

Bolts  are  threaded  any  desired  length,  and  the  check  nut  is 
usually  screwed  on  the  bolt  first,  then  the  ordinary  nut. 

Cap  screws  up  to  and  including  i"  diameter  by  4"  long  are 
threaded  for  three-quarters  of  their  length  and  those  above  i"  in 
diameter  are  threaded  one-half  their  length. 

85.  Tracing  Drawing  €-102.    After  submitting  drawing  0-104 
and  making   a  blueprint  of  tracing  C-ioi,  trace  the  finally 
approved  pencil  drawing  C-io2.     Follow  specific  instructions 
previously  given  in  so  far  as  they  apply  to  this  exercise. 

86.  Tracing  Drawing  €-103.    After  submitting  tracing  C-IO2, 
trace  the  approved  pencil  drawing  0-103.    Follow  specific  instruc- 
tions previously  given  in  so  far  as  they  apply  to  this  exercise. 

87.  Drawing   €-105.      Make   a    mechanical    drawing    from 
sketches  of  the  following  parts: 

Tail  Stock  Center,  see  Fig.  101,  page  144,  also  sketch  #3,  page 
145.  —  Shell,*  see  Fig.  103,  page  144,  also  sketch  #4,  page  146. 
—  Tail  Stock  Spindle,*  see  Fig.  102,  page  144,  also  sketch  #4, 
page  146.  —  Tail  Stock  Spindle  Clamp,*  see  Fig.  113,  page  150,. 

Before  starting  this  drawing  read,  and  prepare  for  examina- 
tion on,  paragraphs,  as  follows: 

*  Dimensions  for  these  parts  are  to  be  obtained  by  making  direct  measure- 
ments of  the  objects  themselves.  See  page  32,  §  29,  and  page  94,  §  62. 


130  ELEMENTS  OF  DRAWING 

Conventional  Methods,  page  87,  §59.  —  Drawing  to  Scale, 
page  90,  §60.  —  Dimensioning  Working  Drawings,  page  94, 
§62. — Notes  on  a  Drawing,  page  97,  §63. — Indicating  the 
Finish  of  Surfaces,  page  98,  §64. — Use  of  Record  Forms  and 
Titles,  page  98,  §  65. 

Follow  specific  instructions  previously  given  in  so  far  as  they 
apply  to  this  exercise.  .  Give  special  attention  to  arranging  the 
views  and  filling  in  the  Bill  of  Material. 

88.  Drawing  C-io6.     Make  a  full-size  longitudinal  section  of 
the  Tail  Stock  with  all  its  parts  assembled.    See  Frontispiece. 

Before  starting  this  drawing  read,  and  prepare  for  examination 
on,  paragraphs,  as  follows: 

Sectioning  and  Sectional  Views,  page  79,  §55. — Assembly 
Drawings,  page  86,  §58. — Dimensioning  Working  Drawings, 
page  94,  §  62.  —  Time  Keeping  in  Drawing,  page  105,  §  71. 

Specific  Instructions.  To  get  all  the  necessary  information 
for  making  this  drawing  refer  to  the  approved  Drawing  C-ic>5, 
also  figures  and  sketches,  as  follows: 

Tail  Stock  Main  Casting,  Fig.  117,  page  152,  also  sketch  #9, 
page  153.  —Tail  Stock  Screw,  Fig.  114,  page  150,  also  sketch  #8, 
page  151.  — Tail  Stock  Hand  Wheel,  Fig.  107,  page  147,  also 
sketch  #5,  page  148.  —  Tail  Stock  Special  Nut,  Fig.  115,  page 
150,  also  sketch  #8,  page  151.  —  Ordinary  Nut,  Fig.  89,  page  128. 

The  title  of  this  drawing  is  ASSEMBLED  TAIL  STOCK. 

Go  over  the  drawing  carefully  before  submitting  same,  to 
see  that  all  lines,  dimensions,  etc.,  are  up  to  the  required 
standard. 

89.  Tracing    Drawing   C-io6.     Follow  specific    instructions 
previously  given  in  so  far  as  they  apply  to  this  exercise. 

90.  Examination  on  Chapter  III.    As  a  final  examination  any 
drawings  assigned  are  to  be  made  of  Lathe  Parts  or  of  any  other 
machine,  and  examination  questions  concerning  previous  work 
(including  Drawing  C-I05)  will  be  asked.     As  a  general  review, 
in  preparation  for  examination,  carefully  read  paragraphs  on 
pages  71  to  116  inclusive;  also  §  12,  page  13,  and  §  28,  page  31. 


CHAPTER  IV 

FREE-HAND   WORKING   SKETCHES 

91.  Introductory.     The  ability  to  make  a  good  free-hand  work- 
ing sketch  is  an  accomplishment  of  great  value  to  the  engineer. 
Much  less  time  is  required  to  make  a  free-hand  sketch  than  a 
mechanical  drawing,  and  in  developing  a  design  it  frequently 
occurs   that   there  are  several  solutions  to   the  problem,  and 
that  the  best  may  be  as  easily  determined  from  a  sketch  as  from 
a  more  elaborate  mechanical  drawing.      If  definite  movements 
must  be  provided  for,  the  vital  positions  of  the  related  parts 
may  be  shown  in  skeleton  outlines  drawn  to  scale  with  instru- 
ments and  each  important  element  or  part  needed  to  be  drawn 
can  be  sketched  in  free-hand. 

In  commercial  drafting  rooms  preliminary  sketches  of  new 
ideas  are  often  filed  away  to  be  worked  up  later  into  detail 
mechanical  drawings.  Such  sketches  serve  as  a  visible  record  of 
the  idea  and  may  prove  valuable  in  establishing  a  priority  claim 
for  a  patent. 

Another  common  use  of  technical  sketches  is  found  in  detail- 
ing parts  that  must  be  renewed  and  for  which  no  drawings  exist. 
Also  in  making  additions  or  alterations,  drawings  of  a  machine 
may  not  be  available  and  yet,  in  order  that  the  new  parts  fit 
into  position  and  act  without  interference,  a  drawing  may  be 
necessary.  Whenever  data  must  be  obtained  from  machines  in 
existence,  a  record  of  all  measurements  is  usually  made  on  a 
free-hand  sketch,  and  the  ability  to  make  a  clear  sketch,  accu- 
rately dimensioned,  complete  in  all  respects,  and  free  from  mis- 
takes and  oversights  so  that  additional  trips  to  the  machine  for 
further  information  are  not  necessary,  is  of  great  value  to  the 
draftsman  or  engineer. 

92.  Free-hand  Copies  of  Working  Drawings.     To  beginners 
the  value  of  making  free-hand  sketches  from  mechanical  draw- 
ings is  to  train  the  hand  to  make  good  free-hand  lines,  and  the 


132  ELEMENTS  OF  DRAWING 

eye  to  judge  proportion,  so  that  the  ability  to  scheme  work  and 
to  plan  details  without  using  the  drawing  instruments  will  be 
acquired. 

93.  Free-hand  Sketches  from  Objects.  It  must  be  understood 
that  working  sketches  as  discussed  here  are  not  perspective 
representations  of  the  object,  but  economical  substitutes  (both 
as  to  time  and  cost  saved)  for  mechanical  drawings.  If  the 
sketch  is  proportioned  accurately  (say  on  cross-section  paper) 
in  accordance  with  measurements  of  the  object,  it  is  in  reality 
a  working  drawing,  differing  from  a  mechanical  drawing  only  in 
that  it  is  made  free-hand. 

In  making  sketches  from  the  object  the  beginner  often  con- 
siders the  dimension  figures  the  only  important  feature  of  the 
work,  and  makes  the  drawing  so  crude  that  other  persons  can- 
not work  from  it.  Such  a  sketch  is  of  very  little  value.  If  a 
sketch  is  to  be  a  permanent  record  it  must  be  so  clear  and 
complete  that  any  one  will  be  able  to  work  from  it,  and  this  can- 
not be  done  unless  the  actual  drawing  is  well  executed.  On 
the  other  hand  if  the  sketches  accurately  represent  the  object 
it  may  not  be  necessary  to  have  all  the  dimensions  recorded 
exactly  as  they  measure  on  the  object.  For  example,  rough 
castings  and  forgings  will  vary  in  thickness,  and  a  part  in- 
tended to  be  symmetrical  about  a  center  line  will  often  deviate 
without  apparent  reason.  The  beginner  must  learn  to  make  a 
distinction  between  dimensions  as  some  measurements  must  be 
recorded  more  exactly  than  others.  For  example,  if  a  pipe 
flange  measured  15!"  in  diameter,  a  15"  flange  could  be  re- 
corded, but  if  the  standard  bolt  circle  of  a  pipe  flange  should 
be  i3i,"  it  must  be  so  recorded,  or  the  flange  will  not  match 
others  drilled  according  to  the  standard.  The  degree  of  refine- 
ment exercised  in  recording  measurements  between  unfinished 
ends  of  a  casting  or  between  one  finished  and  one  rough  end 
will  depend  on  the  size  of  the  casting.  In  very  small  castings, 
such  as  the  small  parts  of  the  lathe,  dimensions  can  be  fre- 
quently "  rounded  off  "  to,  say,  the  nearest  J",  but  measure- 
ments made  between  surfaces  of  parts  which  fit  to  other  parts 
of  a  machine  must  be  made  with  extreme  accuracy.  Center  lines 


FREE-HAND  WORKING  SKETCHES 


133 


and  lines  of  symmetry  must  also  be  carefully  located,  and 
wherever  possible  measurements  should  be  made  from  such 
lines  or  from  finished  surfaces. 

A  sketch  made  without  direct  measurements  of  the  object 
has  no  definite  scale  but  is  proportioned  by  the  eye.  In  such 
cases  the  proper  relation  of  distances,  i.e.,  lengths  of  lines,  is 
secured  by  making  comparisons.  The  relative  width  of  a  part 
is  compared  to  its  length,  and  if  a  detail  on  the  machine  is  one- 
fourth  as  long  as  the  over-all  dimension,  it  should  be  drawn  one- 
fourth  as  long  as  the  over-all  on  the  drawing.  To  assist  in 
making  an  eye  estimate  of  a  distance,  hold  the  pencil  between 
the  eye  and  the  object  and  so  that  the  thumb  nail  can  be  moved 
along  its  length  (see  Fig.  90) ;  sight  along  one  end  of  the  pencil 


Fig.  90.  —  Estimating  Proportion  by  Means  of  the  Eye  and  a  Pencil. 

and  bring  it  in  line  with  the  end  of  the  part  being  measured; 
move  the  thumb  along  the  pencil  until  it  sights  the  opposite  end. 
This  length  along  the  pencil  is  then  compared  with  the  length  of 
the  over-all  dimension  similarly  measured.  In  the  figure  the 
two  diverging  lines  represent  the  limits  of  the  angle  of  sight. 
The  left  eye  usually  is  closed  when  estimating.  The  special 
precautions  necessary  in  this  method  are  that  the  pencil  shall 
always  be  held  the  same  way  and  the  same  distance  from  the  eye, 
and  the  lengths,  being  compared  on  the  object,  shall  be  approxi- 
mately the  same  distance  from  the  eye.  The  pencil  should  be 
held  at  arm's  length  in  making  measurements,  as  this  insures  the 


134  ELEMENTS  OF  DRAWING 

distance  being  kept  constant.  In  this  method  of  estimating  pro- 
portionate lengths  no  one  estimated  length  should  be  greater  than 
a  convenient  length  on  the  pencil,  but  the  distance  from  the  eye 
to  the  object  being  sketched  should  be  such  that  the  estimating 
can  be  on  the  largest  scale  possible.  The  sketch  can  be  made 
to  any  desired  scale,  provided  the  proportions  of  the  sketch  are  kept 
the  same  as  estimated  with  the  pencil.  This  method  of  mak- 
ing a  sketch  of  an  object  is  equivalent  to  tracing  each  line  of  the 
object  on  a  pane  of  glass  which  is  held  at  arm's  length  and  in 
a  plane  at  right  angles  to  an  imaginary  line  drawn  from  the  eye 
to  the  "  center  "  of  the  object. 

94.  Making  Sketches  from  Memory.    The  beginner  should 
occasionally  make  sketches  from  memory.      For  this  purpose 
select  some  simple  object,  or  mechanical  drawing,  and  after 
making  a   careful  study  of  the  object  or  drawing,  make  free- 
hand sketches  comprising  all  necessary  views  and  accurately 
dimension  them  from  memory. 

95.  The  Free-hand  Pencil  Line.    The  first  essential  in^ making 
free-hand  sketches  is  to  learn  to  draw  a  finished  free-hand  line. 
This  requires,  first,  that  the  direction  of  the  line  and,  second,  that 
the  quality  of  the  line  be  correct.     That  is,  the  lines  must 
have  the  proper  direction  and  relation  to  one  another  to  cor- 
rectly represent  the  outline  of  the  object,  and  they  must  also 
be  perfectly  smooth  and  clear-cut,  see  page  78,  §  54,  so  as  to 
present  a  satisfactory  appearance. 

A  good  method  of  drawing  a  free-hand  straight  line  is  as 
follows : 

(1)  Sketch  in  very  lightly  a  series  of  short  dashes  to  follow  as 
closely  as  possible  the  exact  direction  required  of  the  line.     See 
Fig.  91  (a). 

(2)  Correct  the  main  portions  which  are  out  of  true,  locating  these 
by  sighting  along  the  line  and  marking  inaccuracies.    See  Fig.  91  (b) . 

(3)  Retrace  the  line,  which  is  now  true  in  direction  but  "sketchy" 
in   quality,   making   it   uniform   and  of  medium  weight.      See 
Fig.  91  (c). 

(4)  Erase  all  preliminary  work,  and,  as  the  true  line  is  made 


FREE-HAND   WORKING  SKETCHES 


135 


dim  in  the  process,  retrace  it  with  the  longest  strokes  possible,  leav- 
ing it  true  in  direction  and  finished  in  quality.     See  Fig.  Qi(d). 


(a)  First  Attempt  to  Get  Correct  Direction. 


Use  a  HHHH  pencil 

with  conical  point  (see 

page  15,  §  14),  and  as  the     A  — =*=— •*-         •' B 

first  attempt  will  Seldom     (b)  Corrections  Made  at  Points  of  Inaccurate  Direction. 

result  in  a  line  true  in     A -^^  -^- -    -~=\~  •  B 

(c)  Line  Perfected  in  Direction  but  not  Quality. 

A ' B 


either  direction  or  qual- 
ity, all  preliminary  work 
must  be  done  with  very 
light  lines.  The  pencil 
should  be  moved  toward  the  right  [see  Fig.  9 2 (a)]  when  drawing 
lines  which  are  horizontal  or  nearly  so,  and  toward  the  body  or 


(d)  Line  Perfected  in  Both  Direction  and  Quality. 
Fig.  91.  —  Drawing  a  Free-hand  Line. 


(a)  Drawing  a  Horizontal  Free-hand  Line. 


(b)  Drawing  a  Vertical  Free-hand  Line. 
Fig.  92.  —  Method  of  Holding  the  Pencil  to  Draw  a  Free-hand  Line. 

downward  [see  Fig.  92  (b)]  when  drawing  lines  which  are  vertical 
or  nearly  so.     In  drawing  free-hand  lines  it  is  very  important 


136  ELEMENTS  OF  DRAWING 

that  the  pencil  be  held  "  freely  "  and  not  with  a  strained  grip 
and  the  relation  of  the  pencil,  the  fingers  and  the  paper  is 
shown  in  Fig.  92.  Motion  to  the  pencil  or  pen  should  not  be 
given  by  movement  of  the  fingers  but  by  an  easy  movement  of 
the  hand  and  forearm.  When  a  finished  line,  straight  or  curved, 
is  drawn  with  more  than  one  stroke  of  the  pencil,  considerable 
care  must  be  exercised  in  joining  the  segments,  so  that  the  line 
will  be  continuous  and  appear  to  have  been  drawn  at  a  single 
stroke.  A  curved  line  is  drawn  by  locating  a  series  of  points  to 
mark  its  direction,  and  then  proceeding  as  with  the  straight  line. 
Do  not  erase  the  first  lines  drawn  but  only  that  portion  which  does 
not  follow  the  direction  desired.  This  leaves  portions  of  the  line 
to  act  as  a  guide  and  the  final  line  is  brought  to  its  proper  direc- 
tion and  traced  in  somewhat  heavier  than  the  preliminary  lines. 
When  a  line  has  been  drawn  exact  in  direction,  all  preliminary 
work,  and  as  much  of  the  true  line  as  is  necessary  to  destroy  the 
appearance  of  the  short  sketchy  strokes,  is  erased  (using  a  clean 
eraser  and  when  necessary  an  eraser  shield),  and  "the  line  is  finally 
retraced  and  made  of  satisfactory  quality. 

96.  Free-hand  Inked  Lines.  The  beginner  should  not  ink 
any  work  unless  the  original  pencil  work  has  been  checked  and 
approved. 

To  draw  an  inked  free-hand  line,  fill  the  pen  with  an  average 
amount  of  ink,  and,  holding  the  point  at  the  beginning  of  the  line, 
slightly  press  the  pen  until  the  ink  begins  to  flow  (which  is  indi- 
cated by  a  dot  of  ink  on  the  drawing),  then  with  an  even  pressure 
continue  from  that  point,  making  the  line  uniform  in  width  from 
start  to  finish. 

The  width  of  the  free-hand  inked  line  will  depend  on  the 
following  conditions: 

(1)  Fineness  of  the  pen  point. 

(2)  Pressure  exerted  on  the  pen. 

(3)  Condition  of  the   pen  point  as  regards  cleaniness,  i.  e., 
whether  there  is  dried  or  partially  dried  ink  on  the  point. 

(4)  Amount  of  ink  carried  on  the  pen. 

(5)  Speed  at  which  the  pen  is  moved  when  drawing  the  line. 


FREE-HAND   WORKING  SKETCHES  137 

In  general,  free-hand  inked  lines  should  be  formed  with  strokes 
toward  the  draftsman,  or  in  a  right-hand  direction.  (See  Fig.  92, 
page  135.)  Upward  strokes  of  the  pen  should  be  avoided  as  much 
as  possible,  as  the  pen  point  is  liable  to  catch  in  the  drawing 
and  splash  the  ink;  also  this  is  not  the  most  natural  way  to 
make  free-hand  lines. 

Care  must  be  exercised  in  joining  two  segments  of  a  line  when 
inking,  otherwise  the  point  at  which  they  are  joined  is  easily 
detected  and  the  completed  line  will  not  present  a  finished 
appearance. 

To  get  the  best  results  there  should  be  a  steady  and  uniform 
flow  of  ink  from  the  pen,  and  this  is  best  secured  by  frequently 
cleaning  and  refilling  the  pen. 

Too  much  ink  on  the  pen  will  make  a  blot  or  a  line  of  greater 
width  than  desired,  while  too  little  ink  dries  upon  the  points 
and  obstructs  the  free  flow  of  the  ink  from  above.  Frequent 
filling  of  the  pen  tends  to  maintain  an  average  quantity  of  ink 
and  overcomes  both  of  these  difficulties.  If  too  much  ink  has 
been  gathered  on  the  pen  point  touch  the  pen  to  the  neck  of 
the  bottle  to  permit  the  surplus  ink  to  flow  back  into  the  bottle. 

Always  clean  the  pen  point  thoroughly  before  putting  it  away. 

97.  Building  up  a  Sketch.  To  start  a  sketch,  study  the 
part  to  be  represented  and  determine  the  view  which  shows  the 
most  essential  features  and  from  which  related  views  can  be  best 
obtained.  The  relation  of  views  and  the  principles  underlying 
machine  sketching  are  exactly  the  same  as  for  mechanical  drawings. 
(See  page  73,  §  53.) 

Having  determined  the  views  (and  sections,  if  any  are  neces- 
sary) and  the  size  of  the  views,  draw  in  the  main  center  lines  in 
such  a  position  that  when  the  views  are  completed  they  will 
be  arranged  symmetrically  on  the  sheet  and  present  a  neat 
appearance. 

In  beginning  each  view,  draw  several  of  the  most  important 
limiting  lines  first,  and  then  fill  in  the  detail  parts. 

In  general  it  is  best  to  work  from  the  center  of  a  view,  i.e., 
from  the  center  lines,  or  from  the  central  parts  outward. 

Always  complete  the  views  satisfactorily  before  putting  in 
reference  lines,  dimension  lines,  and  arrowheads. 


138  ELEMENTS  OF  DRAWING 

The  outline  of  one  view  should  be  completed  as  far  as  possible 
before  starting  another.  In  working  up  views  it  is  often  con- 
venient to  use  a  strip  of  paper  to  transfer  the  principal  dimen- 
sions from  one  view  to  another.  When  a  circle  or  circular  arc 
is  to  be  drawn,  several  points  should  be  marked  off  equally  distant 
from  the  center  and  the  curve  drawn  through  them. 

In  some  cases  it  may  be  found  best  to  draw  in  the  principal 
dimensions  of  the  object  to  scale  and  finish  up  the  detail  parts 
of  a  view  free-hand;  but  sketching  as  a  rule  is  not  done  to  scale, 
although  the  proportions  are  made  approximately  correct. 

Draw  in  all  the  dimension  lines  and  arrowheads,  but  do  not 
put  in  dimension  figures  until  the  last. 

Draw  all  lines  very  lightly  at  first,  and,  after  inaccuracies  have 
been  corrected,  retrace  the  sketch  and  make  the  lines  of  medium 
weight. 

When  the  correct  outlines  of  all  views  have  been  drawn  of 
medium  weight,  the  entire  sheet  is  to  be  cleaned  with  the  sponge 
rubber  or  art  gum  (see  page  16,  §  15),  and  such  other  erasing  done 
with  the  pencil  eraser  as  is  necessary.  Then  all  the  dimmed  lines 
of  the  views  should  be  retraced  and  made  of  the  desired  weight. 

98.  Title-form  on  Small  Sheets.  Where  the  drawing  sheet  is 
small  a  small  title-form  is  preferable,  and  this  title-form  is  usu- 
ally located  in  the  lower  right-hand  corner. 


TITLE 


MACHINE  DES/GN-S/BLEY  COLLEGE- ITHACA,  NX 


NAME-  _  SECT/ON^.      -DESK  N& 


BEGUN, FINISHED TOTAL  MRS.-. 


INSPECTED ARRVO. \SHEE71. 


Fig.  93.  — Title-form  to  be  used  in  this  work  on  small  sheets. 

There  is  no  accepted  standard  title-form,  but  the  one  shown 
in  Fig.  93  represents  a  general  average  and  will  be  used  in  this 
work  on  all  drawing  sheets  of  the  8"  X  io|"  size. 


FREE-HAND   WORKING  SKETCHES  139 

All  lettering  in  title-form,  unless  otherwise  specified,  is  to  be 
of  the  slant  Gothic  style  and  is  to  be  carefully  arranged  and 
properly  proportioned. 

99.  Size  and  Numbering  of  Sketch  Sheets.  Exercises  in 
sketching  will  be  done  on  small  sheets  of  standard  letter  size 
(8"  X  iof")>  heavy  weight,  cross-section  paper  ruled  on  one  side 
(see  page  5,  §  4)  and  punched  for  standard  #10  Manila  cover. 

The  order  in  which  free-hand  sketch  sheets  are  executed  will 
be  indicated  by  Arabic  numbers  beginning  with  No.  i  and  con- 
tinuing as  far  as  necessary,  and  the  title-form  is  to  be  as  shown 
in  Fig.  93,  page  138. 

•        SET  OF  FREE-HAND  DRAWING  EXERCISES 

100.  Sheet  tfi.  The  sketches  on  this  sheet  consist  of 
a  Shim  (see  Fig.  94)  for  the  bearings,  a  Small  Stud  (see 
Fig.  95)  and  a  Clamp  Stud  (see 
Fig.  96)  for  the  tail  stock  of  the 
Lathe.  Fig.  97,  page  140,  shows 
the  general  layout  of  this  sheet. 

The  exercises  on  this  sheet  give  Fig'  94. -Perspective  of  shim, 
practice  in  making  sketches  of  objects  requiring  only 
one  view,  and  in  drawing  free-hand  lines  and  arrow- 
heads. Note  especially  how  the  diameters  of 
bolts  are  shown.  This  method  applies  to  such 
parts  as  bolts,  screws,  etc.,  but  the  diameters  of 
circular  parts  in  general  should  be  given  on  the 
view  showing  the  circle. 

Before  beginning  this  sheet  determine,  either 
from  referring  to  the  actual  machine  or  else  to 
the  frontispiece,   exactly  where   each   piece   is 
located,  and  its  purpose  on  the  finished  ma- 
7^6.—  chine,  also  what  other  parts  it  must  fit  into  or  against. 
Perspec-       por  fuj]_  information  as  to  the  general  system  to  be 

tive  of  J 

clamp     followed  see  page  175,  Appendix  A. 

Study,  and  prepare  for  examination  on,  paragraphs,  as 
follows : 

Thumb  Tacks,  page  8,  §9.— Pencil  Pointer,  page  14,  §  13. 


140 


ELEMENTS   OF  DRAWING 


I  i 


-1 


I      I 


i 




i    i 
i    i 


!       ! 


-IIHI 


FREE-HAND  WORKING  SKETCHES  141 

—  Lead  Pencils,  page  14,  §  14.  — Erasers  and  Erasures,  page  16, 
§  15.  —  Conventional  Lines,  page  76,  §  54.  —  Checking  Drawings, 
page  113,  §  76.  — Introductory,  page  131,  §  91.  — The  Free-hand 
Pencil  Line,  page  134,  §  95.  — Title-form  for  Sheets,  page  138, 
§  98.  —  Size  and  Numbering  of  Sketch  Sheet,  page  139,  §  99. 

Specific  Instructions,  (a)  Fasten  the  sheet  on  the  small  draw- 
ing board.  (See  page  2,  §  2.)  (b)  Stamp  in  and  fill  out  Title- 
form.  (See  page  138,  §  98.)  The  title  of  this  sketch  is  LATHE 
DETAILS,  (c)  Copy  the  sketches,  being  careful  to  see  that 
the  work  is  correct  in  every  particular. 

Use  a  HHHH  pencil  and  draw  the  sketches  free-hand  on  cross- 
section  paper.  Group  the  figures  centrally  on  the  sheet  in  about 
the  relative  position  and  proportion  shown  in  Fig.  97,  page  140. 

In  making  the  sketch  of  the  Stud,  the  center  line  is  drawn  first 
and  the  sketch  built  symmetrically  about  it.  All  center  lines,  ref- 
erence lines,  dimension  lines,  and  arrowheads  are  to  be  drawn  in. 

Do  not  make  any  measurements  with  scale  or  dividers,  but 
proportion  the  sketches  by  eye.  (See  page  133,  §  93.)  (d)  Thor- 
oughly examine  the  work  to  see  that  nothing  has  been  omitted; 
correct  any  errors,  and  after  inspection  write,  with  ink,  the  Date 
Finished  and  Total  Actual  Hours,  and  submit  the  sheet  for 
checking  and  approval. 

101.  Sheet  #2.  The  sketch  on  this  sheet  (see  Fig.  99,  page  143) 
consists  of  three  views  of  the  main  casting  of  the  Headstock  (see 
Fig.  98,  page  142)  of  the  Lathe.  All  dimension  figures  on  Fig.  99 
represent  the  number  of  spaces  between  arrowheads  and  not  the 
number  of  inches. 

The  purpose  of  this  exercise  is  to  illustrate  the  use  of  cross- 
section  paper;  to  provide  practice  in  making  free-hand  curved 
lines,  and  in  making  a  sketch  of  an  object  which  requires  several 
views. 

The  relation  of  the  different  views  of  this  sketch  to  one  another 
must  be  carefully  studied,  and  the  sketch  not  merely  copied. 

Before  starting  this  work  read,  and  be  prepared  for  examina- 
tion on,  paragraphs,  as  follows: 

Cross-section  Paper,  page  5,  §4. — Erasing  Shield,  page  17, 
§  16. — Projection  and  Projected  Views,  page  73,  §  53. — Num- 


142  ELEMENTS  OF   DRAWING 

ber  and  Arrangement  of  Views,  page  83,  §56. — Dimension- 
ing Working  Drawings,  page  94,  §62.  —  Indicating  the  Finish 
of  Surfaces,  page  98,  §  64.  —  Free-hand  Copies  of  Working 
Drawings,  page  131,  §  92. 


Fig.  98.  —  Perspective  of  Main  Casting  of  Headstock. 

Determine  the  location  and  purpose  of  the  Headstock.  See 
Frontispiece. 

Specific  Instructions,  (a)  Fasten  the  sheet  on  the  small  draw- 
ing board.  (See  page  2,  §  2.)  (b)  Stamp  in  and  fill  out  title- 
form.  (See  page  138,  §  98.)  The  title  of  this  sketch  is  LATHE 
DETAILS,  (c)  Having  located  main  center  lines,  refer  to  the 
"  space  dimensions  "  given  in  Fig.  99  and  accurately  locate  a 
sufficient  number  of  points  to  determine  the  outline  of  the  side 
view  (a),  which  is  then  sketched  in  very  lightly.  The  end  views 
are  next  drawn. 

After  all  views  have  been  completed  in  a  satisfactory  manner, 
clean  the  sheet  and  retrace  all  lines,  making  them  clear-cut  and 
of  the  desired  weight. 

Having  gone  over  the  work  and  brought  it  to  the  highest 
standard  possible,  submit  the  sheet  for  approval. 

102.  Sheet  #3.  The  sketches  on  this  sheet  represent  a  Face 
Plate  (see  Fig.  100,  page  144),  a  Tail  Stock  Center  (see  Fig.  101, 


144 


ELEMENTS  OF  DRAWING 


page  144),  and  a  Special  Nut  (see  Fig.  80,  page  117)  for  head- 
stock  spindle.  Fig.  104  shows  the  general  layout  of  this  sheet. 
The  purpose  of  the  exercises  on  this 
sheet  is  to  provide  practice  in  free-hand 
sketching  and  in  making  a  working  draw- 
ing which  will  have  all  dimensions,  notes, 
and  other  data  necessary  for  the  construc- 
tion of  the  parts  in  the  shop.  Before 
starting  this  sheet  study  the  system  of 
dimensioning,  noting  especially  how  circles, 
arcs,  angles,  and  tapers  are  dimensioned, 
and  how  related  dimen- 
sions are  kept  together. 

Study    and    prepare  Fig.  101.— Perspective  of 
for  examination  on  paragraphs  as  follows: 

Detail  Drawings,  page  85,  §>;7.  —  Conventional  Methods, 
page  87,  §  59.  —  Indicating  the  Finish  of  Surfaces,  page  98, 
§  64.  — Use  of  Record  Forms  and  Titles,  page  98,  §  65.  —  Making 
Sketches  from  Memory,  page  134,  §  94. 

What  is  meant  by  "  counterbore  "  and  "  countersink."  How 
do  you  determine  the  number  of  threads  per  inch  on  a  given 
diameter  ? 

Follow  the  specific  instructions  previously  given  in  so  far  as  they 

apply  to  this  sheet. 


Fig.  100.  —  Perspective  of 
Face  Plate. 


103.    Sheet     #4. 

Fig.  ^.-Perspective  of  Tailstock  Spindle.  ^  ^^   Qn   ^ 

sheet  are  sketches  of  the  Tail  Stock  Spindle  (see  Fig.  102)  and 
Shell  (see  Fig.  103). 

These  exercises  illustrate  the  method 
of  representing  simple  symmetrical  parts 
in  the  clearest  way  possible  with  the 
minimum  amount  of  drawing.  Fig. 
105  gives  the  general  layout  of  this 

J  Fig.  103.  — Perspective  of  Shell. 

sheet. 

Before  starting  this  work  read,  and  be  prepared  for  examina- 
tion on,  paragraphs,  as  follows: 


FREE-HAND  WORKING  SKETCHES 


145 


146 


ELEMENTS  OF  DRAWING 


FREE-HAND   WORKING  SKETCHES 


147 


Sectioning  and  Sectional  Views,  page  79,  §  55.  — Notes 
on  a  Drawing,  page  97,  §  63.  —  The  Title  form  on  a 
Drawing,  page  100,  §  66. 

104.   Sheet  #5.    The  exercises  on  this  sheet  consist  of 

sketches  of  the  Clamp  Bolt  (see  Fig.   106)   the  Hand 

Wheel  (see  Fig.  107)  and  the  End  Cap  (see  Fig.  108). 

Fig.  109,  page  148,  gives  the  general  layout  of  sheet. 

The  system  of  dimensioning  is  the  main  point  to  be 

noted  in  sketching  these 
parts.  Dimensions  which 
are  related  are  kept  to- 
gether, as,  for  example,  the 
partial  dimensions  making 
up  the  length  of  the  Clamp 
Bolt.  These  are  given  on 

0  Fig.  1 06.— 

the  same  side  of  the  view  Perspective 
and  not  scattered.     Withof^tmp 
partial  dimensions,  an  over- 
all dimension   is   given,   which  of 
course   must   be   the   sum  of  the 
partial  dimensions. 
Note  also  the  method  of  dimensioning  curves;  the  different 
views  in  which  the  different  diameters  are  shown  on  the  draw- 
ing; the  method  of  "  turning  up  "  the  section 
in  the  arm  of  the  hand  wheel,  and  that  in  the 
section  of  the  hand  wheel  the  arms  are  not 
sectioned,  although  the  cutting  plane  passes 
through  them. 


Fig.  107. — Perspective  of  Hand  Wheel. 


Fig.  1 08.  — Perspective 
of  End  Cap. 


105.  Sheet  #6.  The  exercises  on  this  sheet 
consist  of  three  undimensioned  views  of  the 
Clamp  (see  Fig.  in,  page  150).  Fig.  no, 
page  149,  gives  the  general  layout  of  this  sheet  which  is  to  be 
copied  and  then  the  dimensions  filled  in  from  measurements 
taken  on  the  Clamp  that  the  drawing  illustrates. 

Before  drawing  this  sheet  read,  and  be  prepared  for  examina- 
tion on,  paragraphs,  as  follows: 


148 


ELEMENTS  OF  DRAWING 


FREE-HAND  WORKING  SKETCHES 


149 


ELEMENTS  OF  DRAWING 


Machinist's  Calipers,  Dividers  and  Steel  Rule,  page  32,  §  29. 
—  Choice  of  Scale  in  Drawing,  page  93,  §  61.  —  Dimensioning 

Working  Drawings,  page  94,  §  62. 
—  Notes  on  a  Drawing,  page  97, 
§  63.  —  To  make  a  Pencil  Draw- 
ing, page  1 08,  §  74. — Free-hand 
Sketches  from  Objects,  page  132, 

§93- 


1 06.   Sheet  #7.    Make  sketches 
of  the  Tool  Rest  Support  Slide 
(see  Fig.  112)  and  of  Clamp  for 
113).      This  sheet  is  to  be  made 


Fig.  in.  —Perspective  of  Tailstock 
Clamp  Strip. 

Tailstock  Spindle  (see  Fig. 
directly  from  these  parts. 

Before  starting  the 
work  read,  and  be 
prepared  for  exam- 
ination on,  para- 
graphs, as  follows: 

Projection     and  pig.  112.  — Perspective  of  Tool  Rest  Support  Slide. 

Projected  Views, 

page   73,    §  53.  —  Drawing  to  Scale,  page  90,   §  60. — Notes 

on  a  Drawing,  page  97,  §  63.  — Building  up  a  Sketch,  page  137, 

§  97- 

Determine  the  purpose  and 
location  of  the  above  parts  on 
the  lathe. 

107.  Sheet  $8.  Make 
sketches  of  the  Tailstock 
Screw  (see  Fig.  114)  and 
the  Nut  (see  Fig.  115)  following  the  general  layout  shown 
in  Fig.  116,  page  151.  Determine  the  location  and  purpose 
of  each  of  these  parts  on  the  lathe  and  be  prepared  for 


Fig.  114.  —Perspective  of  Tailstock  Screw. 


Fig.  113.— Perspective  of  Tailstock 
Spindle  Clamp. 


Fig.  115. — Perspective 
of  Tailstock  Nut. 


FREE-HAND   WORKING   SKETCHES 


* 


152 


ELEMENTS   OF  DRAWING 


examination    on    paragraph    59,   page   87,    with   reference   to 
Conventional  Methods. 

Copy  sketch  and  fill  in  dimension  figures  from  measurements 
made  on  the  objects  which  are  illustrated. 

This  sheet  illustrates  the  method  of  showing  and  dimensioning 
key  ways  and  the  Acme  National  Thread  (see  page  88,  section  D, 
drawing  c).  Notice  that  the  direction  of  the  thread  shown  on 
the  section  of  the  nut  is  reversed  from  that  on  the  screw  and 
be  able  to  explain  the 
reason  for  this. 


1 08.  Sheet  $9.  Make  a 
working  sketch,  showing 
three  views  of  the  main 
casting  of  the  Tailstock 
(see  Fig.  117). 

Keep  that  portion  of 
the  surface  of  the  draw- 
ing not  in  use  covered 
with  a  clean  piece  of  paper 
and  avoid  smearing  the 
drawing.  Fig.  119,  page 
153,  shows  the  general  lay- 
out for  this  sheet. 


Fig.  117.  —  Perspective  of  Main  Casting  of  Tailstock. 


109.  Sheet  #10.  Make  working  sketches 
directly  from  the  Bearing  Cap  (see  Fig.  118)  and 
The  Stationary  Flange  (see  Fig.  120,  page  154). 

no.   Sheet  #11.     Make  working  sketches  of 
the  Cone  Pulley  (see  Fig.  121,  page  154),  on 
Fig.  i  is.— Perspective    ordinary  standard  size  paper  (not  cross-section 

of  Bearing  Cap.  \  j  ^  ,1  n 

paper)  and  see  that  the  views  are  well  pro- 
portioned. In  practice  sketches  are  frequently  made  on  unruled 
paper. 


in.   Sheet  #12.     Make  a  copy  of  the  sketch  of  the  pattern 
and  core  box  for  the  Cone  Pulley  (see  Fig.  122,  page  155). 


FREE-HAND  WORKING  SKETCHES. 


153 


154 


ELEMENTS   OF  DRAWING 


112.  Inking  Sheet  #i.  The  purpose  of  inking  this  sheet  is  to 
give  practice  in  making  straight  free-hand  inked  lines. 

Where  only  a  limited  number  of  pieces  are  to  be  made  from  a 
drawing,  it  frequently  happens  that  the  work  does  not  warrant 
the  expense  of  making  a  tracing  and  a  penciled  sketch  is  not 
sufficiently  permanent,  therefore  an  inked  sketch  is  made. 

Before  starting  this  exercise  study,  and  be 
prepared  for  examination  on,  paragraphs,  as 
follows : 

Drawing  Ink,  page  18,  §  18.  —  Ordinary  Pens, 
page  18,  §  19. — Penholders,  page  20,  §20. — 
Conventional  Lines,  page  76,  §  54.  —  The  Free- 
hand Inked  Line,  page  136,  §  96. 

To  avoid  spoiling  a  pencil  drawing  practice 
making  an  inked  line  on  a  piece  of  scrap  paper 
before  starting  to  ink  the  penciled  work.  Do  not 
start  inking  until  the  penciled  sketch  has  been 
checked  and  approved. 


Fig.  120.  — Perspec- 
tive of  Small  Flange. 


113.  Inking  Sheet  #3.     The  purpose  of  inking  this  sheet  is 
to  give  practice  in  making  inked  curved  lines  free-hand. 

114.  Inking    Sheet 

#i  i .  This  exercise  gives 
practice  in  inking  on 
ordinary  paper. 

115.  Examination  on 
Chapter  IV.  As  a  final  ex- 
amination, any  sketches 
assigned  are  to  be  made 
in  pencil  or   in   ink   of 
Lathe  Parts  or  parts  of 
any  other  machine,  this 

WOrk      tO      be     done     On  Fig.  12I. -Perspective  of  ConePulley. 

plotting  or  on  plain  paper  as  directed.  Also  examination  ques- 
tions concerning  the  main  subject  matter  of  this  chapter  will 
be  asked. 


FREE-HAND   WORKING   SKETCHES 


155 


CHAPTER  V 

ISOMETRIC   DRAWING   AND   SKETCHING 

116.  Introductory.  Isometric  drawings  are  often  preferable 
to  mechanical  drawings  because  they  are  very  easily  understood, 
even  by  those  who  have  little  or  no  knowledge  of  technical 
drawing. 

While  mechanical  drawings  can  be  made  so  that  they  com- 
pletely represent  an  object  both  as  to  its  form  and  dimensions, 
several  views  are  usually  required  to  represent  the  object  fully; 
and  in  order  to  read  and  understand  such  drawings  it  is  necessary 
to  visualize  the  object  from  these  views.  This  usually  requires 
considerable  study  on  the  part  of  the  reader,  and  the  disadvan- 
tages of  mechanical  drawings  can  be  largely  overcome  by  the 
use  of  isometric  drawings  to  represent  the  object.  Isometrics 
are  coming  to  be  used  much  more  frequently  in  illustrating  pip- 
ing plans  and  layouts,  structural  details,  "  bird's  eye  "  views  of 
buildings,  etc.,  although  they  have  already  been  extensively 
used  in  making  patent  office  drawings  and  in  illustrating  tech- 
nical books  and  catalogues.  Isometrics  are  also  especially  useful 
in  illustrating  shop  processes  and  methods,  and  certain  manu- 
facturing firms  operating  under  the  so-called  "scientific  manage- 
ment "  use  this  method  of  giving  very  definite  and  minute 
instructions  to  the  workmen,  as,  for  examples,  the  best  method 
of  fastening  a  certain  piece  of  work  in  a  machine,  the  proper  way 
to  take  cuts  from  the  piece,  etc.  Some  of  the  large  steel  manu- 
facturers are  using  isometric  drawings  practically  to  the  exclusion 
of  mechanical  drawings. 

Some  of  the  advantages  of  isometric  drawings  are:  (a)  they 
can  be  easily  made  and  understood;  (b)  they  give,  in  a  single 
view,  the  information  that  requires  two  or  more  views  if  a  me- 
chanical drawing  is  made  use  of;  (c)  practically  no  ability  to 
"  visualize  "  is  necessary  in  reading  isometric  drawings,  and  in 
this  respect  they  resemble  perspective  drawings  but  possess  an 

156 


ISOMETRIC    DRAWING  AND   SKETCHING  157 

advantage  over  perspective  drawings  in  that  they  can,  in  a 
limited  way,  be  measured  and  dimensioned  similarly  to 
mechanical  drawings. 

Some  of  the  disadvantages  of  isometric  drawings  are :  (a)  they 
show  an  object  "  distorted  "  and  often  make  it  appear  unreal; 
(b)  they  can  be  measured  (i.e.,  "  scaled  ")  only  in  certain  direc- 
tions; (c)  angles  shown  in  isometric  cannot  be  measured  in 
degrees;  (d)  all  circles  show  in  isometric  as  ellipses,  and  an  ellipse 
is  more  difficult  to  draw  with  instruments  than  a  circle,  but  this 
is  rather  an  advantage  in  free-hand  isometric  drawing. 

117.  Principles.     Isometric  drawing  is  based  on  the  principles 
of  isometric  projection,  but  it  is  beyond  the  scope  of  this  text  to 
take  up  the  discussion  of  the  principles  underlying  this  art.     For 
the  purpose  of  this  work  it  will  be  necessary  to  state  only  two  new 
principles  not  included  in  orthographic  projection,  viz: 

(1)  The  object  to  be  represented  is  so  placed  with  reference 
to  the  projection  plane  that  instead  of  presenting  a  single  face  for 
projection,  three  faces  at  right  angles  to  each  other  and  repre- 
senting the  length,  width,  and  thickness  of  the  object  will  be 
equally  inclined  to  this  projection  plane  and  thus  all  three  faces 
are  presented  in  a  single  view. 

(2)  With  an  object  placed  as  stated  in  principle  (i)  above,  all 
vertical  lines  of  the  object  will  be  drawn  vertical,  and  all  hori- 
zontal lines  of  the  object  will  be  drawn  at  60  degrees  to  the 
vertical  or  at  30  degrees  to  a,' true  horizontal  line. 

These  principles  can  be  best  illustrated  by  making  an  isometric 
drawing  of  a  cube.  See  §  118,  this  page. 

118.  Isometric  Drawing  of  a  Cube.     A  mechanical  drawing 
of  a  cube  is  shown  in  Fig.  123  (a)  and  an  isometric  drawing  of  the 
same  size  cube  is  shown  in  Fig.  123  (b),  see  page  158. 

To  construct  the  isometric  drawing,  draw  the  vertical  line  O-Y 
and  lay  off  B-F  equal  in  length  to  the  edge  B-F  of  the  cube; 
that  is,  equal  to  b'-f. 

From  O  draw  0-X  to  the  left  and  O-Z  to  the  right,  each  line 
making  120  degrees  with  O-Y;  that  is,  each  of  these  lines  will 
make  30  degrees  with  a  horizontal  line. 


158 


ELEMENTS   OF  DRAWING 


On  O-X  lay  off  a  distance  equal  to  the  length  of  the  edge 
B-A  of  the  cube;  that  is,  equal  to  b'-a'. 

On  O-Z  lay  off  a  distance  equal  to  the  edge  B-C  of  the  cube; 
that  is,  equal  to  b'-c'. 

From  A  draw  A-D  equal  and  parallel  to  B-C.  From  C  draw 
C-D  equal  and  parallel  to  B-A.  The  rhombus*  A-B-C-D  is 
the  isometric  drawing  of  the  square  top  a-b-c-d  of  the  cube. 


Y 

(a)  Mechanical.  (b)  Isometric. 

Fig.  123.  — Drawing  of  Cube. 

From  C  draw  C-G  equal  and  parallel  to  B-F  and  from  F  draw 
F-G  equal  and  parallel  to  B-C.  The  rhombus  F-B-C-G  is  the 
isometric  drawing  of  the  square  face/'-ft'-c'-g'  of  the  cube. 

The  face  A-B-F-E  is  similarly  determined. 

1 19.  Definitions.  The  following  definitions  will  be  more  easily 
remembered  by  referring  to  Fig.  123  (b),  this  page. 

(a)  The  isometric  axes  are  three  intersecting  lines  drawn  at 
1 20  degrees  to  one  another,  one  of  which  lines  is  vertical,  and  the 
other  two  will  be  30  degrees  to  the  true  horizontal  and  in  opposite 
directions.     The  isometric  axes  are  sometimes  referred  to  as  the 
X,  Y,  and  Z  axes. 

(b)  The  isometric  origin  is  the  intersection  of  the  isometric 
axes  and  it  is  usually  marked  O. 

(c)  An  isometric  line  is  one  which  is  parallel  to  any  one  of  the 
three  isometric  axes. 

(d)  A  non-isometric  line  is  one  which  is  not  parallel  to  any  one 
of  the  three  isometric  axes. 

*  The  rhombus  (or  rhomb)  is  an  oblique  parallelogram  whose  sides  are  all  equal. 


ISOMETRIC    DRAWING  AND   SKETCHING 


159 


(e)  Measurements  can  only  be  made  on  isometric  lines  and 

can  never  be  made  on  non-isometric  lines.  That  is,  an  isometric 
drawing  of  a  solid  can  be  measured  or  scaled  in  only  three  direc- 
tions and  of  a  plane  figure  in  only  two  directions,  these  directions 
always  being  parallel  to  the  isometric  axes.  This  principle  is 
illustrated  in  Fig.  123  (b),  page  158.  Lines  which  lie  in  the  face 
B-C-G-F  can  be  scaled,  or  measured,  if  parallel  to  O-Z  or  0-Y 
but  not  if  parallel  to  O-X.  This  will  be  understood  if  diagonals 
are  drawn  from  B  to  G  and  from  F  to  C,  for  though  these  diagonals 
are  actually  equal  in  length  they  do  not  project  equally. 


120.  Isometric  Drawing  of  a  Circle.  The  isometric  drawing 
of  a  circle  is  always  an  ellipse.  To  determine  points  on  the  ellipse 
enclose  the  circle  within  a  square  as  shown  in  Fig.  124  (a)  and 
next  draw  the  construction  lines  1-2,  3-4,  5-6,  etc.,  so  as  to  in- 
tersect on  the  circle  at  points  i,  j,  k,  I.  Let  it  be  assumed  that 
the  circle  lies  in  a 
vertical  plane.  Then 
the  isometric  drawing 
of  the  circumscribed 
square  a-b-c-d  can  be 
drawn  exactly  as  if  it 
were  the  face  F-G-C-B 
shown  in  Fig.  123  (b), 
page  158.  The  sides 
of  the  square  a-d  and 
d-c  are  made  to  coin- 
cide with  the  isometric 
axes  O-Y  and  O-Z,  respectively,  in  Fig.  124  (b),  hence  D-6 
of  Fig.  124  (b)  can  be  measured  off  equal  to  d-6  of  Fig.  124  (a) 
and  D-i  of  Fig.  124  (b)  can  be  made  equal  to  d-i  of  Fig.  124  (a). 
The  points  j  and  8  of  Fig.  1 24  (b)  are  found  in  a  similar  manner, 
and  through  the  points  i,  6,  etc.,  the  construction  lines  are  drawn 
parallel  to  D-C  and  D-A ;  these  lines,  such  as  1-2,  and  6-5,  are 
isometric  lines  and  their  intersection  /  is  the  isometric  position 
of  j,  a  point  on  the  circle.  All  other  points  on  the  circle,  such  as 
£,  7,  H,  etc.,  are  similarly  located  and  the  ellipse  which  is  drawn 
through  these  points  is  the  isometric  drawing  of  the  circle.  The 


(a)  Mechanical. 


A 

y 

(b)  Isometric. 
Fig.  124.  — Drawing  of  Circle. 


i6o 


ELEMENTS   OF   DRAWING 


ellipse  through  Ii-Ji-Ki-Li  represents  the  isometric  drawing  of 
the  same  circle  when  it  lies  in  a  vertical  plane  parallel  to  the 
plane  of  the  isometric  axes  O-Y  and  O-X.  The  ellipse  through 
Iz-Jz-Kz-Lz  represents  the  isometric  drawing  of  the  circle  when 
it  lies  in  a  horizontal  plane.  The  points  on  these  ellipses  are  found 
exactly  as  the  points  I-J-K-L  of  the  first  ellipse  were  found. 


121.  Approximate  Method  of  Making  an  Isometric  Drawing 
of  a  Circle.  The  ellipse  when  constructed  as  described  in  §  120, 
page  159,  represents  the  true  isometric  drawing  of  the  circle,  but 

an  approximate  method  which  is  much 
simpler  and  at  the  same  time  sufficiently 
accurate  for  most  purposes  is  shown  in 
Fig.  125.  The  sides  C-D  and  D-A  are 
bisected  respectively  by  the  lines  B-A 
and  E-C,  which  are  drawn  directly  from 
A  and  C  with  the  30-60  degree  triangle. 
With  C  as  a  center  and  C-E  as  a  radius 
describe  the  arc  E-F.  With  A  as  a 
center  and  with  C-E  as  a  radius  describe 
the  arc  G-B.  With  the  intersection 
point  P  of  the  lines  A-B  and  C-E  as  a  center  and  with  P-E  as 
a  radius  describe  the  arc  E-B.  Similarly  describe  the  arc  F-G. 
If  this  work  has  been  accurately  done  the  resulting  figure  will 
appear  as  a  "  smooth "  ellipse.  The  ellipses  in  the  vertical 
planes  can  be  similarly  constructed. 


Fig.  125.  —  Approximate  Method 
of  Drawing  an  Isometric  of  a 
Circle. 


122.  Isometric   Drawing 
Straight     and     Curved 
Lines.   Assume  that  any 

Bh 

plane  outline  as  shown 
in  Fig.  126  (a)  is  to  be 
represented  in  isometric. 
Circumscribe  a  square  or 
rectangle  about  the  figured  3  *s 
to  be  drawn  in  isometric 
as  shown  in  Fig.  126 
(a).  Through  important  Fig.  126.- 


of   a  Plane   Figure   Composed   of 


\ 

£_ 

~J 

/ 

\E 

\ 

F 

J 

/ 

^  — 

(a)  Mechanical. 


J?" 

(b)  Isometric. 
Drawing  of  Any  Plane  Figure. 


ISOMETRIC    DRAWING   AND   SKETCHING 


161 


points  on  the  figure  draw  lines  parallel  to  the  sides  of  the  circum- 
scribed square.  These  lines  will  be  isometric  lines  of  the  isometric 
drawing,  hence  I-K,  K-6,  K-F,  F-j,  etc.,  of  Fig.  i26(b)  are 
drawn  respectively  equal  to  I-K,  K-6,  K-F,  F-j,  etc.,  of  Fig. 
126  (a);  the  isometric  position  of  the  points  such  as  E,  F,  K 
being  found  by  laying  off  A-i,  1-2,  2-3,  3-4,  etc.,  D-I,  I- 77, 
77-777,  etc.,  of  Fig.  126  (b),  equal  to  the  corresponding  distances 
of  Fig.  126  (a).  Through  these  points,  lines  are  drawn  parallel 
to  the  proper  sides  of  the  rhombus  and  the  intersections  of  these 
lines  determine  the  isometric  position  of  the  required  points. 

Fig.  126  (b)  shows  the  figure  in  the  horizontal  and  in  the  two 
different  vertical  isometric  planes. 

123.  Isometric  Drawing  of  a  Cube  Cut  by  a  Plane.  Assume 
the  cube  cut  by  a  plane  through  its  edge  and  at  any  angle.  First 
draw  one  face  of  the 
cube  in  orthographic 
projection,  and  draw 
the  lines  O-/J,  0-jo, 
0-45,  etc.,  from  the 
corner  0  and  making 
15  degrees,  30  degrees, 
etc. ,  respectively,  with 
the  line  O-O,  see  Fig. 


(d) 
Fig.  127.  — Cube  cut  by  Planes. 


(e) 


127  (a).  In  Fig.  127  (b)  is  shown  the  isometric  drawing  of 
this  face  of  the  cube  with  the  lines  0-15,  O-jo,  etc.,  represented 
as  making  15  degrees,  30  degrees,  etc.,  with  O-O.  In  this  figure 
the  included  corresponding  angles  #re  not  equal  to  those  of 


162 


ELEMENTS    OF    DRAWING 


Fig.  127  (a),  but  the  distances  0-15,  O-jo,  etc.,  measured  on 
the  bottom  line  of  Fig.  127  (b)  are  equal  to  the  corresponding 
distances  of  Fig.  127  (a). 

In  Fig.  127  (c)  a  cube  is  shown  in  isometric  as  it  would  appear  if 
cut  by  a  plane  through  the  edge  O-A ,  and  at  60  degrees  to  O-O. 

In  Fig.  127  (d)  a  cube  is  shown  in  isometric  as  if  cut  by  two 
planes,  one  at  15°,  the  other  at  60°  with  the  back  top  edge  0-D. 

In  Fig.  127  (e)  a  cube  is  shown  in  isometric  as  it  would  appear 
if  cut,  first,  as  in  Fig.  127  (c),  and  then  as  in  127  (d). 


124. 


Fig.  128. 


Isometric  Drawing  of  Wall.  Fig.  1 28  (a)  shows  a  mechan- 
ical (or  orthographic)  drawing  of  a  rectangular 
object,  and  Fig.  128  (b)  shows  isometric  draw- 
ings of  the  block  in  three  different  positions. 

(c)   shows 


Fig.  128  (c)  snows  an 
ordinary  isometric  draw- 
ing which  represents  a 
wall  built  of  blocks  as 
shown  in  Fig.  128  (b). 
Fig.  128  (d)  shows  a 
different  view  of  a  wall 
similar  to  that  of  Fig. 
128  (c)  but  having  the 
horizontal  lines  in  a 
downward  direction 
instead  of  upward  as 
in  previous  work. 
Drawing  the  horizon- 
tal downward  is  called 
reversing  the  axes,  and 
this  method  can  be 
used  to  show  the  lower 
face  of  an  object,  rep- 
resenting it  as  if  tilted 
backward  instead  of 
forward,  the  method 
of  construction,  how- 
ever,  being  the  same 

(d)  Isometric  with  Axes  Reversed. 
-Isometric  Drawings  of  Wall  Built  of  Blocks.       in  either 


ISOMETRIC   DRAWING   AND   SKETCHING 


I63 


Make  a  drawing  of  a  cube 


125.  Isometric  of  a  Cylinder. 

that  will  just  enclose  the 
cylinder  then  draw  the 
ellipse  within  the  rhom- 
bus that  represents  the 
top  of  the  cube  See  Fig. 
129.  Likewise  construct 
the  base  of  the  cube,  and 
connect  the  top  and  the 
base  with  tangent  lines 
as  shown  in  the  figure. 

126.  Isometric  of  Screw  Threads.     In  order  to  save  time  the 
true  forms  of  screw  threads  are  never  shown  in  isometric  draw- 
ings.    The  conventional  method  of  representing  the  threads  is 


Fig.  129.  — Isometric  Drawings  of  Cylinder  in  Different 
Positions. 


\ 


Fig.  130.  — Nut  and  Bolt  with  Conventional 
Isometric  Thread. 

shown  in  Fig.  130.  To  make  such  a  drawing  consider  the  body 
of  the  bolt  as  a  cylinder  and  proceed  as  in  §  125,  this  page.  The 
ellipse  which  represents  the  base  of  the  cylinder  is  to  be  repeated 
in  the  proper  positions  to  indicate  the  threads,  the  distances  be- 
tween the  ellipses  usually  being  taken  equal  to  the  pitch  of  the 
thread;  that  is,  the  distance  between  the  ellipse  centers  is  equal 
to  the  thread  pitch.  See  "  centers  "  at  i,  2,  j,  etc.,  in  Fig.  130. 


ELEMENTS    OF   DRAWING 
The  internal  thread  shown  in  the  Nut  is  similarly  constructed. 

127.   Hollow  Cylinder  with  a  Quarter  Section  Removed.     It  is 

very  often  advisable  to  show  an  object  with  a  section  removed 
as  in  Fig.  131. 

This  drawing  is  of  a  Lathe  Spindle  (see  Frontispiece,  also 
Fig-  147 >  Page  i?2)-     To  construct  such  a  drawing  proceed  as  in 


Fig.  131.  — Isometric  of  Lathe  Spindle 
with  Section  removed. 

§  125,  page  163,  to  obtain  the  outline  of  the  cylinder.  Next,  con- 
sider the  hole  in  the  cylinder  as  a  second  cylinder  and  draw  -in  its 
outline.  To  "  take  out  "  the  section  a  plane  such  as  A-B-D-C 
is  assumed  passed  vertically  through  the  axis  A-B  of  the  spindle 
and  a  plane,  such  as  A-E-F-B,  is  assumed  passed  horizontally 
through  the  axis.  In  this  construction  note  that  the  centers  of 
all  ellipses  are  on  the  axis  A-B  and  their  respective  distances 
from  the  ends  of  the  spindle  are  measured  on  this  axis. 

128.    Offset  Construction  in  Isometric  Drawing.     It  is  not 

always  necessary  to  enclose  the  object  completely  in  a  cube  or 
rectangle,  as  described  in  §  122,  page  160,  in  order  to  make  an 
isometric  drawing.  See  also  §  125,  page  163.  It  frequently 
occurs  that  the  isometric  lines  can  be  drawn  more  readily  by  the 
offset  construction  as  illustrated  in  Fig.  132,  page  165. 


ISOMETRIC   DRAWING  AND   SKETCHING 


129.  Isometric  Drawing  of  a  Sphere.  The  isometric  drawing 
of  a  sphere  is  represented  by  a  circle.  To  determine  the  radius  of 
this  circle,  make  an  isometric  drawing  of  a  circle  having  the  same 


i^.  132.  — Offset  Construction. 


diameter  as  the  sphere.  The  radius  of  the  circle  which  represents 
the  sphere  will  be  equal  to  one-half  the  major  axis  of  the  ellipse 
which  represents  the  circle.  In  Fig.  133  is  shown  a  sphere  of 
diameter  D.  The  dashed  ellipse  shown  in  Fig.  133  (b)  is  the 


(b) 
Fig-  133.  — Drawing  of  a  Sphere. 

isometric  drawing  of  a  circle  having  a  diameter  D.  The  radius, 
R,  of  the  circle  which  represents  the  isometric  drawing,  of  the 
sphere  is  one-half  the  length  oj  the  major  axis  of  the  ellipse. 

To  draw  a  half-sphere  construct  the  outline  of  the  sphere  as 
described  above.    Next  draw  the  ellipse  which  represents  a  great 


i66 


ELEMENTS    OF   DRAWING 


circle  of  the  sphere.     In  Fig.  134  (a)  is  shown  the  lower  half  of  a 
sphere  and  in  Fig.  134  (b)  is  shown  the  upper  half. 


(a)  Lower  half.  (b)  Upper  half. 

Fig.  134. —  Isometric  of  a  Half  Sphere. 


Fig.  135. —  Isometric  of 
One-eighth  Sphere. 


To  draw  one-eighth  of  a  Sphere  construct  the  sphere  as  de- 
scribed above  and  next  draw  the  great  circles  at  right  angles  to 
one  another  as  shown  in  Fig.  135. 

130.  Isometric  Drawing  of 
Lathe  Cap.    To  get  an  idea 
of  the  exact  shape  of  the  Lathe 
Cap  see  Frontispiece  and  Fig. 
148,  page  172.     The  Cap  is  a 
combination  of  a  cylinder  (see 
§  125,  page  163),  a  half  sphere 
(see  §  129,  page  165)  and  of 
V   threads    (see    §  126,  page 

163). 

Fig.  136  shows  an  isometric 
drawing  of  the  Lathe  Cap  with 
one-quarter  section  removed. 

131.  Size  and  Numbering 

Fig.  i36.-lsometric  of  Lathe  Cap.  Qf   Sketch   Sheetg>       Exercises 

in  isometric  sketching  are  to  be  done  on  small  sheets  of  standard 
letter  size  (8"  X  io|")  heavy  weight  isometric-ruled  paper  (see 
§  4,  page  5),  the  ruling  on  one  side  only.  The  paper  is  to  be 
punched  for  standard  No.  10  Manila  cover.  As  previously  stated, 
one  of  the  disadvantages  of  making  isometric  drawings  me- 
chanically is  due  to  the  frequent  necessity  of  drawing  ellipses. 
This,  however,  is  an  advantage  in  free-hand  sketching,  since  the 
ellipse  is  more  easily  drawn  free-hand  than  the  circle.  The  chief 


ISOMETRIC   DRAWING  AND   SKETCHING  167 

objection  to  making  isometric  sketches  is  due  to  the  difficulty  of 
maintaining  the  thirty-degree  angle.  This  difficulty  can  be 
entirely  overcome  by  the  use  of  isometric  ruled  paper,  see  Fig.  i  (b) , 
page  5.  This  paper  has,  besides  the  regular  vertical  and  hori- 
zontal ruling  of  the  ordinary  cross-section  paper,  also  lines  ruled 
at  thirty  degrees  to  the  horizontal.  This  ruling  insures  the  proper 
slope  to  all  isometrically  horizontal  lines  and  the  draftsman  needs 
no  other  instruments  than  a  pencil  and  measuring  rule  to  make 
isometric  drawings  of  the  most  complex  nature. 

The  order  in  which  free  hand  isometric  sketch  sheets  are  exe- 
cuted will  be  indicated  by  Roman  numbers  beginning  with  I  and 
continuing  as  far  as  necessary.  For  the  general  system  to  be 
followed  see  Appendix  A,  page  175. 

SET   OF   FREE-HAND    ISOMETRIC   EXERCISES. 

132.  Sheet  I.  The  purpose  of  this  sheet  is  to  give  practice  in 
making  an  Isometric  Drawing  of  a  simple  object  and  also  to  bring 
out  some  of  the  elementary  principles  of  Isometric  Sketching. 

Before  starting  to  draw,  read,  and  be  prepared  for  examination 
on,  paragraphs,  as  follows: 

Ruled  Paper,  page  5,  §4. — Lead  Pencil,  page  14,  §14.- 
Erasers  and  Erasures,  page  16,  §  15.  —  The  Free-hand  Pencil 
Line,  page  134,  §95.  —  Introductory,  page  156,  §  116.  —  Prin- 
ciples, page  157,  §  117. — Isometric  Drawing  of  a  Cube,  page  157, 
§  118. — Definitions,  page  158,  §  119.  —  Isometric  Drawing  of  a 
Circle,  page  159,  §  120.  —  Size  and  Numbering  of  Sketch  Sheets, 
page  1 66,  §  131,  and  for  information  on  the  general  system  to  be 
followed  see  page  175,  Appendix  A. 

Exercise  on  Sheet  I. 
This  exercise  con- 
sists of  an  Isometric 
sketch  of  Tool  Rest 
Support  Slide  for  the 
Lathe,  see  Fig.  137; 

,  '  .      .  Fig.  137-— Perspective  of  Tool  Rest  Support  Slide. 

also  Frontispiece. 

Specific  Instructions  for  Executing  Sheet  I.  Tack  down  the 
isometric  ruled  sheet,  stamp  in  the  title-form  (see  Fig.  93,  page 
138)  in  the  lower  right-hand  corner  of  sheet,  and  neatly  write  with 
ink  the  wording  of  the  title. 


1 68 


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ISOMETRIC   DRAWING  AND   SKETCHING  169 

The  title  of  sheet  I  is  Support  Slide. 

Do  not  use  a  straight-edge  in  any  of  this  free-hand  course  as 
this  will  seriously  impair  the  value  of  the  work. 

Make  a  pencil  perspective  sketch  of  the  Support  Slide  on  central 
portion  of  the  sheet,  and  to  about  the  scale  shown  in  Fig.  138. 
Dimension  the  sketch,  and  when  the  sheet  has  been  cleaned  and 
all  the  lines  made  clear  cut  and  of  the  desired  weight  and  con- 
struction, and  the  work  is  thoroughly  checked,  submit  it  for  in- 
spection and  approval.  Compare  this  sketch  with  Fig.  51  (b), 
page  74,  and  determine  in  your  own  mind  which  conveys  the 
necessary  information  with  the  fewer  lines,  also  which  would  be 
the  more  readily  understood  by  the  average  person  who  would 
use  drawings. 

133.  Sheet  II.  The  purpose  of  these  exercises  is  to  give 
further  practice  in  making  Isometric  Sketches  of  simple  objects. 

Before  starting  this  exercise,  read  and  be  prepared  for  exami- 
nation on,  paragraphs,  as  follows: 

Approximate  Method  of  making  an  Isometric  Drawing  of  a 
Circle,  page  160,  §  121.  —  Isometric  Drawing  of  a  Plane  Figure 
composed  of  Straight  and  Curved  Lines,  page  160,  §122. — 
Isometric  of  a  Cylinder,  page  163,  §  125.  —  Isometric  of  a  Screw 
Thread,  page  163,  §  126. 

Exercises  on  Sheet  II.  The  exercises  on  this  sheet  consist  of 
pencil  Isometric  Sketches  of  a  Key  (see  Fig.  139),  of  a  Shim  (see 


Fig.  139.  —  Perspective  Fig.  140.  —  Perspective 

of  Key.  of  Shim. 

Fig.  141.  —  Perspective 

of  Stud. 


Fig.  142.  — Perspective  of  Fiber  Fig.  143.  — Perspective 

or  Steel  Washer.  of  Special  Nut. 

Fig.  140),  of  a  Stud  (see  Fig.  141),  of  a  Washer  (see  Fig.  142),  and 
of  a  Nut  (see  Fig.  143),  all  of  these  being  parts  of  the  Speed  Lathe 
as  shown  on  Frontispiece. 


170 


ELEMENTS  OF  DRAWING 


ISOMETRIC   DRAWING  AND   SKETCHING 


171 


Specific  Instructions.  Stamp  the  title-form  (see  Fig.  93,  page 
138)  in  lower  right-hand  corner  of  sheet  and  write  in  ink  the 
wording  of  the  title. 

The  title  of  this  sheet  is  Speed  Lathe  Details. 

Sketch  in  these  parts  similar  to  the  way  they  are  shown  in  Fig. 
144,  dimensioning  the  figures. 

Having  perfected  the  sketches,  submit  for  approval. 

Compare  the  sketches  on  this  sheet  with  similar  parts  shown 
in  Fig.  82,  page  118,  and  Fig.  97,  page  140,  and  in  your  own 
mind  determine  which  is  the  best  and  quickest  method  of 
representing  these  objects. 

134.   Sheet  III.    The  purpose  of  the  exercises  on  this  sheet  is 
to  give  practice  in  making  Isometric  Sketches  directly  from  the 
object  and  in  dimensioning  these  sketches,  the 
dimensions  being  obtained  by  direct  measure- 
ment of  the  object. 

Exercises  and  Specific  Instructions.  The 
exercises  on  this  sheet  consist  of  Isometric 
Sketches  of  a  Collar  (see  Fig.  145)  and  of  a 
Bearing  (see  Fig.  146)  made  from  direct 
observation  of  these  parts,  and  all  dimensions 
and  notes  necessary  are  to  be  put  in,  the 
dimensions  being  obtained  by  measurements 
made  directly  on  the  Collar  and  the  Bearing. 

Stamp  in  and  fill  out  the  title  form. 

The  title  of  this  sheet  is  Speed  Lathe  Details. 

Check  the  drawing  thoroughly  and  submit 
for  approval. 


Fig.  I4S-  —  Perspective 
of  Collar. 


Fig.  146.  —  Perspective 
of  Bearing. 


135.  Sheet  IV.  The  purpose  of  this  exercise  is  to  give  practice 
in  making  an  isometric  sketch  in  ink  and  in  showing  an  object 
with  a  quarter  section  removed,  the  sketch  being  on  plain  paper. 

Before  starting  to  draw,  read  and  be  prepared  for  examination 
on  paragraphs  as  follows: 

Freehand  Inked  Line,  page  136,  §  96.  —  Isometric  Drawing  of 
a  Cube  cut  by  a  Plane,  page  161,  §  123.  — Hollow  Cylinder  with 
a  Quarter  Section  Removed,  page  164,  §  127. 


172 


ELEMENTS   OF  DRAWING 


Exercise  and  Specific  Instructions.  Tack  down  a  standard 
size  sheet  of  plain  paper  of  good  quality  to  take  ink  and  make  an 
Isometric  Sketch,  in  pencil  first,  of  Lathe  Spindle  (see  Fig.  147) 


Fig.  147.  — Perspective  of  Tailstock  Spindle. 

similar  to  Fig.  131,  page  164,  except  the  key  way  is  to  be  shown 
and  the  sketch  dimensioned  from  the  object.     The  sketch  having 

been  perfected  in  pencil,  it  is  to  be  neatly 

inked  in. 

The  title  of  this  sheet  is  Lathe  Spindle. 


Fig.  148.  — Perspective 
of  Lathe  Cap. 


136.  Sheet  V.  Make  an  isometric  drawing 
of  a  Lathe  Cap  (see  Fig.  148),  with  a  quarter 
section  removed  (see  Fig.  136,  page  166). 

Before  starting  to  draw,  read  and  be  prepared 
for  examination  on  paragraphs  as  follows : 
Isometric  Drawing  of  a  Sphere,  page  165,  §  129.  —  Isometric 
Drawing  of  a  Lathe  Cap,  page  166,  §  130. 

Specific  Instructions.     Stamp  in  and  fill  out  the  title  form. 
The  title  of  this  sheet  is  Lathe  Cap. 

Make  all  lines  very  light  until  the  correct  outline  is  obtained; 

clean  the  sheet  and  sketch  in  the  object  clear  cut  and  complete. 

Submit  the  sheet  for  approval. 

137.  Sheet  VI.  An  isometric  sketch  is  to 
be  made  of  a  Lathe  Shelf  Bracket  (see  Fig. 
149),  showing  the  object  in  two  different  posi- 
tions, as  illustrated  in  Fig.  1 50,  page  1 73.  This 
sketch  is  to  be  finished  up  in  pencil  and  then 
inked  in  freehand. 

Before  starting  this  drawing,  read,  and  be 
prepared  for  examination  on,  paragraphs,  as  F~  149._ perspective  of 

follows:  Shelf  Bracket. 

Isometric  Drawing  of  a  Wall,  page  162,  §  124.  —  Offset  con- 
struction in  Isometric  Drawing,  page  164,  §  128. 
The  title  of  this  sheet  is  Shelf  Bracket. 


ISOMETRIC  DRAWING  AND   SKETCHING 


173 


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174  ELEMENTS  OF  DRAWING 

138.  Examination  on  Chapter  V.  As  a  final  examination  on 
this  chapter  make  an  Isometric  Drawing  of  Tool  Rest  Support 
(see  Fig.  151)  or  of  any  other  parts  of  the  Lathe  or  of  parts  of 
any  other  machine  assigned,  on  plain  or  ruled  paper,  and  in 
pencil  or  ink  as  directed.  Also  study  the  subject  matter  con- 
tained in  §  1 1 6,  page  156,  to  §  132,  page  167,  in  preparation  for 
examination. 


Fig.  151.  —  Perspective  of  Tool  Rest  Support. 


APPENDIX   A. 


DRAWING  ROOM  SYSTEM. 

139.  Commercial  Drawing  Rooms.  In  practically  all  com- 
mercial drawing  rooms  work  is  carried  on  under  some  fixed 
system,  the  nature  of  which  depends  upon  the  character  and 
scope  of  the  work  to  be  accomplished.  Such  systems  usually 
require  that  drawings  be  made  to  certain  standard  sizes;  that 
a  certain  title  form  providing  for  specific  information  be  used; 
that  certain  styles  of  lettering  be  used;  that  certain  conventions 
and  abbreviations  be  used,  and  so  forth.  The  value  of  doing 
the  work  of  this  course  under  an  efficient  system  can  therefore 
be  readily  understood,  and  it  is  expected  that  either  the  system 
as  outlined  below  or  a  system  provided  by  the  instructor  will 
be  followed. 

(a)  General  Method  of  Procedure.  Having  secured  instru- 
ments and  supplies  (see  §  2,  page  2)  proceed  with  the  drawing 
course  beginning  with  the  set  of  Freehand  Lettering  Exercises 
as  outlined  in  §  38,  page  44  to  §  52.  Next  take  up  the  set 
of  Mechanical  Drawing  Exercises  as  outlined  in  §  79,  page  116, 
to  §  91.  Then  take  up  the  set  of  Freehand  Drawing  Exercises 
as  outlined  in  §  100,  page  139,  to  §116,  and  finally  take  up  the  set 
of  Isometric  Freehand  Sketching  Exercises  as  outlined  in  §  132, 
page  167,  to  §  139. 

In  working  up  the  exercises  on  each  sheet  or  drawing  proceed 
in  the  following  manner: 

1.  Read  all  text  matter  assigned  and  be  prepared  for  ex- 
amination on  same. 

2.  Tack  down  the  sheet  or  drawing  (see  §  73,  page  107)  and 
where  necessary  draw  in  the  border  line  (see  §  72,  page  106). 

3.  Put  the  title  form  in  the  lower  right-hand  corner.     Write, 
in  with  ink  the  wording  of  the  title  form  as  far  as  possible. 

4.  Proceed  with  the  actual  drawing  as  instructed  in  the  text. 
NOTE.     Satisfactory  progress  can  be  made  only  when  the 

beginner  learns  to  criticise  his  own  work  intelligently  as  it 

175 


176  APPENDIX 

proceeds  and  when  he  forms  the  habit  of  making  at  once  any 
changes  found  necessary  from  his  own  criticism  or  suggested 
by  the  instructor. 

Before  requesting  the  instructor  to  finally  inspect  a  piece  of  work, 
the  student  must  check  every  exercise  and  bring  the  work  as  a  whole 
up  to  the  highest  standard  of  perfection  of  which  he  is  capable. 

When  the  exercises  appear  satisfactory  to  the  instructor,  he 
signs  his  name  (or  initials)  in  the  title  form  after  the  word  "  IN- 
SPECTED." The  student  is  then  to  write  with  ink  the  DA  TR 
FINISHED  and  the  TOTAL  ACT  UAL  HO  URS  expended  on 
the  work;  it  is  then  deposited  in  some  prescribed  place  in  order 
that  the  instructor  may  further  check  it  if  thought  best. 

If  deficiencies  are  found  in  checking  the  work,  it  will  be  returned 
once  for  the  student  to  make  the  corrections  and  changes  indi- 
cated. Exceptional  care  must  be  taken,  when  making  changes 
to  avoid  spoiling  the  work. 

Work  not  neatly  and  accurately  corrected  will  not  be  approved. 

All  changes  and  corrections  indicated  must  be  made  at  the 
earliest  possible  date  and  the  corrected  work  immediately 
returned  to  the  proper  place  by  the  student. 

If  the  quality  of  work  done  on  any  part  of  the  sheet,  drawing, 
tracing,  or  plate  is  unsatisfactory  and  cannot  be  brought  to  the 
required  standard  of  perfection  by  the  student,  it  must  be  repeated 
until  all  requirements  are  met. 

When  inspected  work  is  not  returned  to  the  student  within  a 
reasonable  length  of  time,  this  indicates  that  the  instructor  in 
further  checking  has  found  no  serious  deficiencies  and  has  given 
the  work  final  approval. 

In  no  case  is  a  student  to  trace  a  drawing,  make  a  drawing  from 
a  sketch,  or  do  any  advanced  work  which  depends  upon  work  previ- 
ously done,  unless  the  original  has  been  finally  approved  by  the 
proper  instructor. 

(b)  Sizes  of  Drawings.  All  lettering,  sketching  and  computing 
work  is  to  be  done  on  "  sheets  "  measuring  8"  by  loj".  (See 
page  44,  §  37;  page  139,  §  99;  page  166,  §  131.)  All  mechanical 
drawing  is  to  be  done  on  paper  or  tracing  cloth,  measuring  12" 
by  18",  this  size  to  be  designated  by  a  Capital  C.  (See  page 
106,  §  72.) 


APPENDIX  177 

(c)  Position  of  Sheet  or  Drawing  on  the  Board.    All  sheets 
and  drawings  are  to  be  tacked  down  with  the  short  dimensions 
to  the  sides  unless  other  instructions  are  given.     The  punched 
holes  of  the  "  sheets  "  should  be  at  the  top  and  the  punched 
holes  of  the  "  drawings  "  on  the  left-hand  side.     (See  page  107, 

§73.) 

(d)  Border  Lines.     No  border  line  is  to  be  used  on  small 
"  sheets,"  but  on  "  drawings  "  the  border  line  shown  in  Fig.  73, 
page  1 06,  is  to  be  used. 

(e)  Numbering    and    Lettering    of    Sheets    and    Drawings. 
Sheets  of  Lettering  will  be  designated  by  capital  letters,  begin- 
ning with  A.     Sheets  of  Freehand  Drawing  will  be  designated 
by  Arabic  numbers   beginning   with   /.     Sheets   of   Isometric 
Freehand   Drawing   will    be    designated   by   Roman    numbers 
beginning  with  I.     Mechanical  Drawings  will  be  designated  by 
the  word  "  DRAWING"  followed  by  the  capital  Letter  C,  which 
is  then  followed  by  the  number  of  the  drawing  —  the  first  draw- 
ing being  101,  thus  DRAWING  C  —  101. 

(/)  Title  Form  and  its  Location.  On  small  "  sheets  "  of 
Lettering,  Sketching,  and  Computing  the  small  Title  Form  as 
shown  in  Fig.  93,  page  138,  is  to  be  used.  For  Mechanical 
Drawings  of  the  12"  by  18"  size  the  large  Title  Form  as  shown  in 
Fig.  69,  page  100,  is  to  be  used.  The  wording,  however,  is  to  be 
appropriately  modified. 

On  sheets  the  title  form  is  to  be  located  in  the  lower  right-hand 
corner.  On  drawings  with  border  lines  the  title  form  is  to  be 
located  in  the  lower  right-hand  corner  just  within  the  border 
lines,  unless  other  instructions  are  given. 

(g)  Bill  of  Material  and  its  Location.  On  drawings  requiring 
a  bill  of  material  the  Bill  of  Material  form  shown  in  Fig.  70, 
page  101,  is  to  be  used  and  is  to  be  located  just  above  the  title 
form,  unless  other  instructions  are  given. 

(h)  Style  of  Lettering.  The  Freehand  Slant  Gothic  alphabet 
is  to  be  used.  (See  Fig.  42,  page  57;  Fig.  43,  page  61;  §  44, 
page  62;  §  45,  page  68). 

(i)  Conventions  and  Abbreviations  as  given  in  the  text 
matter  are  to  be  used  whenever  necessary,  and  uniformity  in 
this  regard  is  to  be  strictly  maintained. 


INDEX. 

A. 

A,  description  of  the  letter,  p.  47,  §  38;  p.  63,  §  47. 
Abbreviation  "&,"  description  of,  p.  54,  §  41. 

for  "feet,"  p.  95,  §  62. 

for  "radius,"  p.  97,  §  62. 

for  materials,  p.  103,  §  67. 
Ability  to  letter,  p.  34,  §  3 1. 
Acme  thread,  p.  89,  §  59. 

Adjacent  part  conventionally  shown,  p.  89,  §  59. 
Alphabet,  Gothic  (see  also  Letters,  description  of),  p.  34,  §  31. 
Angles,  dimensioning  of,  p.  97,  §  62. 
Appendix  A,  p.  175,  §  139. 
Architect's  scale,  p.  29,  §  27. 
Area,  cross-sectioning  an,  p.  82,  §  55. 
Arrangement  of  views,  p.  75,  §  53. 

and  number  of  views,  p.  83,  §  56. 
Arrowheads,  p.  77,  §  54. 

position  of,  p.  95,  §  62. 
Arrows,  direction,  in  lettering,  p.  38,  §  34. 
A.  S.  M.  E.  standard  screws,  p.  126,  §  84. 
Assembly  drawings,  p.  86,  §  58. 
Axes,  isometric,  p.  158,  §  119. 

isometric  reversed,  p.  162,  §  124. 


B. 

B,  description  of  the  letter,  p.  53,  §  41;  p.  64,  §  47. 

Ball-pointed  pen,  p.  3,  §  2;  p.  19,  §  19. 

Bearing  conventionally  shown,  p.  87,  §  59. 

Bill  of  material,  general  description  of,  p.  101,  §  67. 

used  in  this  work,  p.  101,  §  67. 

Blocking  or  laying  out  a  drawing,  p.  84,  §  56;  p.  93,  §  61. 
Blotter,  p.  4,  §  2;  p.  33,  §  30. 
use  of  a,  p.  in,  §  75. 

Blot  on  a  drawing,  to  remove,  p.  in,  §  75. 
Blue  print  paper,  p.  2,  §  2;  p.  6,  §  7. 

changes  on,  p.  116,  §  78. 
method  of  making,  p.  7,  §  7. 
method  of  using,  p.  116,  §  78. 
Blue  printing  machines,  p.  116,  §  78. 
Blue  print,  exercise  in  making  a,  p.  121,  §  81. 

frame,  p.  116,  §  78. 
Board,  drawing,  p.  2,  §  2;  p.  7,  §  8. 

use  of,  p.  107,  §  73. 

Bolts,  table  of  U.  S.  Standard,  p.  127,  §  84. 
Border  lines,  layout  of,  in  this  work,  p.  106,  §  72. 

use  of,  on  a  drawing,  p.  106,  §  72. 
Bottle  holder,  p.  112,  §  75. 
Bow  dividers,  p.  3,  §  2;  p.  27,  §  24. 
pencils,  p.  3,  §  2;  p.  27,  §  25. 
design  of,  p.  27,  §  25. 
selection  of,  p.  27,  §  25. 

179 


l8o  INDEX 

Bow  pencil^,  to  test,  p.  28,  §  25. 
use  of,  p.  28,  §  25. 
pens,  p.  3,  §  2;  p.  28,  §  26. 
to  test,  p.  29,  §  26. 
use  of,  p.  28,  §  26. 

Broken  lines,  conventional,  p.  76,  §  54;  p.  89,  §  59. 
Broken  sections,  conventional,  p.  87,  §  59. 
Building  up  a  drawing  or  sketch,  p.  137,  §  97. 

C. 

C,  description  of  the  letter,  p.  52,  §  41;  p.  64,  §  47. 
Calipers,  machinists',  p.  4,  §  2;  p.  32,  §  29. 
inside,  p.  32,  §  29. 
outside,  p.  32,  §  29. 
use  of,  p.  32,  §  29. 
Cap  screws,  p.  128,  §  84. 
Capital  letters,  characteristics  of  curved,  p.  51,  §  41. 

characteristics  of  straight  line,  p.  44,  §  38. 
description  of,  p.  44,  §  38;  p.  51,  §  41. 

detailed  description  of  each  letter  (see  Letters,  description  of), 
spacing  of,  p.  40,  §  35. 

Capital  and  small  letters,  spacing  between,  p.  42,  §  35. 
Carbonate  of  soda,  p.  4,  §  2;  p.  116,  §  78. 
Care  of  instruments,  p.  i,  §  i. 
Center  lines,  p.  78,  §  54. 

in  lettering,  p.  37,  §  34. 
on  a  drawing,  p.  108,  §  74. 
Center  line,  symbol  for,  p.  78,  §  54. 
Changes  on  a  drawing,  p.  99,  §  65. 

blue  prints,  p.  116,  §  78. 
tracings,  p.  17,  §  15. 
Checking  drawings,  p.  113,  §  76. 
Checking,  how  to  proceed  in,  p.  113,  §  76. 
Choice  of  dimensions,  p.  95,  §  62. 

a  scale,  p.  93,  §  61. 
Circle,  dimensioning  a,  p.  97,  §  62. 
Circle,  isometric  drawing  of,  p.  159,  §  120. 

approximate  method  of  making  isometric  drawing  of,  p.  160,  §  121. 
Cleaning  drawings,  p.  16,  §15. 
Cloth,  tracing,  p.  2,  §  2;  p.  6,  §  6. 
Colored  inks,  p.  18,  §  18. 
Compasses,  p.  3,  §  2;  p.  23,  §  22. 
design  of,  p.  23,  §  22. 
use  of,  p.  25,  §  22. 
Compass,  head-joint  design,  p.  23,  §  22. 

socket-joint  design,  p.  24,  §  22. 
Conventions,  p.  87,  §  59. 

common,  p.  88,  Fig.  65. 
Conventional  drawing  of  bearing,  p.  87,  §  59. 
drilled  hole,  p.  90,  §  59. 
hollow  part,  p.  87,  §  59. 
lines,  p.  76,  §  54;  p.  89,  §  59. 
methods,  p.  87,  §  59. 
method  of  showing  an  adjacent  part,  p.  89,  §  59. 

screw  threads  in  isometric,  p.  163,  §  126. 
method  of  showing  timber,  p.  87,  §  59. 
National  Acme  thread,  p.  89,  §  59 
screw  thread,  p.  72,  §  52;  p.  89,  §  59. 
sectioning,  p.  81,  §  55. 
shaft,  p.  87,  §  59. 
square  thread,  p.  89,  §  59. 


INDEX  l8l 

Conventional  steel  shape,  p.  90,  §  59. 
tapped  hole,  p.  90,  §  59. 
V  thread,  p.  89,  §  59. 
Construction  of  lines,  p.  76,  §  54. 
Cored  holes,  p.  97,  §  62. 
Covers,  Manila,  p.  4,  §  2. 
Cross  sectioning,  p.  82,  §  55. 

conventional,  p.  8r,  §  55;  p.  90,  §  59. 
instrument  for,  p.  82,  Fig.  64. 
Cross  section,  p.  79,  §55;  p.  83,  §  55. 

paper,  p.  2,  §  2;  p.  5,  §  4. 
Crow-quill  pen,  p.  3,  §  2;  p.  19,  §  19. 
Cube,  isometric  drawing  of,  p.  157,  §  118. 

cut  by  a  plane,  p.  16*,  §  123. 
Curves,  French  or  irregular,  p. 2, §2;  p.  13, §12. 

use  of,  p.  13,  §  12. 

Cylinder,  hollow,  shown  in  isometric,  p.  164,  §  127. 
isometric  of,  p.  163,  §  125. 

D. 

D,  description  of  the  letter,  p.  52,  §  41;  p.  63,  §  47. 
Definitions,  isometric  drawings,  p.  158,  §  119. 

Description  of  capital  letters  (see  also  Letters,  description  of),  p.  44,  §  38;  p.  51,  §  41. 
numerals,  (see  detailed  description  of), 
small  letters,  (see  also  Letters,  description  of),  p.  60,  §  47. 
Detail  drawings,  p.  85,  §  57. 

paper,  p.  5,  §  3. 

Dimensioning,  p.  34,  §  31;  p.  94,  §  62. 
angles,  p.  97,  §  62. 
castings,  p.  95,  §  62. 
circles,  p.  97,  §  62. 
cored  holes,  p.  97,  §  62. 

drawings  and  sketches,  p.  94,  §  62;  p.  132,  §  93. 
fillets,  p.  97,  §  62. 
of  holes,  p.  89,  §  59. 
radiuses,  p.  97,  §  62. 
refinement  in,  p.  95,  §  62. 
rough  castings,  p.  95,  §  62. 
rules  for,  p.  94,  §  62. 
tapers,  p.  97,  §  62. 
tapped  holes,  p.  97,  §  62. 
threaded  pieces,  p.  97,  §  62. 
working  drawings,  p.  94,  §  62. 
Dimension  lines,  p.  77,  §  54. 

numbers,  p.  95,  §  62. 
Dimensions,  purpose  of,  p.  94,  §  62. 
checking,  p.  95,  §  62. 
choice  of,  p.  95,  §  62. 
limits  in,  p.  95,  §  62. 
location  of,  p.  96,  §  62. 
not  to  scale,  p.  95,  §  62. 
numbers,  expressing,  p.  95,  §  62. 
on  model  letters,  p.  38,  §  34. 
overall,  p.  96,  §  62. 
related,  p.  96,  §  62. 

Direction  arrows  in  lettering,  p.  38,  §  34. 
Distance  between  letters,  p.  39,  §  35. 
Dividers,  p.  3,  §  3;  p.  26,  §  23. 

bow,  p.  3,  §  2;  p.  27,  §  24. 
machinists',  p.  4,  §  2;  p.  33,  §  29. 

use  of,  p.  33,  §  29;  p.  26,  §  23. 


182  INDEX 

Drawing,  an  assembly,  p.  86,  §  58. 

arrangement  and  number  of  views  on,  p.  83,  §  56. 
blocking  out  a,  p.  84,  §  56;  p.  93,  §  61. 
boards,  p.  2,  §  2;  p.  7,  §  8. 
care  of,  p.  8,  §  8. 
design  of,  p.  7,  §  8. 
use  of,  p.  107,  §  73. 
border  line  for  a,  p.  106,  §  72. 
building  up  an  assembly,  p.  86,  §  58. 

a  detail,  p. 137,  §  97- 
care  of,  p.  15,  §  14. 
changes  on  a,  p.  99,  §  65. 
checking  a,  p.  113,  §  76. 
cleaning  a,  p.  16,  §  15. 
conventional,  p.  87,  §  59. 
definitions  in  isometric,  p.  158,  §  119. 
detail,  p.  85,  §  57. 

dimensioning  a  working,  p.  94,  §  62. 
exercises  in  mechanical,  p.  116,  §  79. 
free-hand,  p.  139,  §  100. 
isometric  free-hand,  p.  167,  §  132. 
ink,  p.  3,  §  2;  p.  18,  §  18;  p.  no,  §  75. 

care  of,  p.  18,  §  18. 

selection  of,  p.  18,  §  18. 

use  of,  p.  no,  §  75. 
instruments,  p.  3,.§  2. 
isometric,  p.  156,  §  116. 
isometric,  of  a  cube,  p.  157,  §  118. 
paper,  p.  2,  §  2;  p.  4,  §  3. 

selection  of,  p.  4,  §  3. 

part  or  reference  number  on  a,  p.  90,  §  57;  p.  104,  §  69. 
pencils,  p.  3,  §  2;  p.  14,  §  14. 

to  sharpen,  p.  15,  §  14. 

pens,  unsatisfactory  results  with,  p.  no,  §  75. 
perspective,  p.  71,  §  52. 
position  in  which  to  tack  down,  p.  108,  §  73. 
mechanical,  Chapter  III,  p.  71,  §  52. 
notes  on  a,  p.  73,  §  52;  p.  97,  §  63. 
numbering  and  size  of,  in  this  work,  p.  103,  §  68. 
record  on  a,  p.  98,  §  65. 
recording  patterns  on  a,  p.  104,  §  70. 
requirements  of  a,  p.  72,  §  52. 
room  system,  Appendix  A,  p.  175,  §  139. 
scale  of  a,  p.  93,  §  61. 

selection  of,  p.  14,  §  14 

size  and  numbering  of,  in  this  work,  p.  103,  §  68. 
symbols  on  a,  p.  72,  §  52. 
time  keeping  in,  p.  105,  §  71. 
title-form  on  a,  p.  100,  §  66. 
to  fasten  on  board,  p.  107,  §  73. 
to  ink  a,  p.  no,  §  75. 
to  make  a  pencil,  p.  108,  §  74. 
to  protect  a,  p.  112,  §  75. 
to  scale,  p.  90,  §  60. 
Drilled  hole,  conventional,  p.  90,  §  59. 


E. 

E,  description  of  the  letter,  p,  45  §  38;  p.  64,  §47. 
Eight,  description  of  the  numeral,  p.  59,  §  44. 
Element  of  adjacency,  definition  of,  p.  40,  §  35. 


INDEX  183 


Elevation,  front  and  side,  p.  75,  §  53- 
Ellipse,  the  sloping,  p.  50,  §  40. 
Engineer's  scale,  p.  29,  §  27. 
Erasers,  p.  3,  §  2;  p.  16,  §  15. 
care  of,  p.  17,  §  15. 
selection  of,  p.  16,  §  15. 
use  of,  p.  16,  §  15. 
Erasing  shield,  p.  3,  §  2;  p.  17,  §  16. 
Erasures,  how  to  make,  p.  17,  §  15. 

on  tracing  cloth,  p.  115,  §  77. 
Examination  in  free-hand  drawing,  p.  154,  §  115. 

isometric  free-hand  drawing,  p.  174,  §  138. 
lettering,  free-hand,  p.  69,  §  51. 
mechanical  drawing,  p.  130,  §  90. 
Exercises  in  free-hand  drawing,  p.  139,  §  100,  etc. 

isometric  drawing,  p.  167,  §  132,  etc. 
lettering,  p.  44,  §  38,  etc. 
mechanical  drawing,  p.  116,  §  79,  etc. 
numerals,  p.  60,  §  45,  etc. 


F. 

F,  description  of  the  letter,  p.  45,  §  38;  p.  66,  §  47. 
Fastening  the  paper  or  tracing  cloth  on  the  board,  p.  107,  §  73. 
Fasteners,  paper,  p.  4,  §  2. 

Faulty  lines,  p.  in,  §  75. 

Feet,  abbreviation  for,  p.  95,  §  62. 

Fillets,  dimensioning,  p.  97,  §  62. 

Finish  mark,  p.  98,  §  64. 

Finished  line,  p.  78,  §  54. 

Finish  of  a  surface,  p.  98,  §  64. 

Fit,  force,  p.  95,  §  62. 

Five,  description  of  the  numeral,  p.  59,  §  44. 

Flat  scale,  p.  29,  §  27. 

Force  fit,  p.  95,  §  62. 

Formula  for  making  blue-print  paper,  p.  7,  §  7. 

Four,  description  of  the  numeral,  p.  58,  §  44. 

Fractions,  slope  of,  p.  60,  §  45. 

how  to  print,  p.  60,  §  45. 
Free-hand  copies  of  working  sketches,  p.  131,  §  92. 

drawing  exercises,  set  of,  p.  139,  §  100,  etc.,  see  also  Chapter  IV,  Table 

of  Contents, 
examination  in,  p.  154,  §  115. 

inked  lines,  p.  136,  §  96. 

isometric  exercises,  set  of,  p.  167,  §  132,  see  also  Chapter  V,  Table  of 

Contents, 
examination  in,  p.  174,  §  138. 

lines,  to  draw,  p.  134,  §  95. 

penciled  lines,  p.  134,  §  95. 

sketching,  p.  132,  §  93. 

sketches  made  directly  from  objects,  p.  133,  §  93. 

working  sketches,  p.  131,  Chapter  IV. 
French  curves,  p.  2,  §  2;  p.  13,  §  12. 
Front  elevation,  p.  75,  §  53-. 

G. 

G,  description  of  the  letter,  p.  52,  §  41;  p.  64,  §  47. 

Gothic  alphabet  (see  also  Letters,  description  of),  p.  34,  §  31. 
Guide  lines  in  lettering,  p.  37,  §  34. 


184  INDEX 

H. 

H,  description  of  the  letter,  p.  45,  §  38;  p.  65,  §  47. 
Headings  and  titles,  design  of,  p.  69,  §  49. 
Headstock,  assembly  of  lathe,  Frontispiece. 
Holder,  bottle,  p.  112,  §  75. 

pen,  p.  3,  §  2;  p.  20,  §  20. 
Hole,  drilled  or  tapped,  p.  90,  §  59. 

cored,  p.  97,  §  62. 
Holes,  dimensioning,  p.  89,  §  59. 

tapped,  dimensioning,  p.  97,  §  62. 
Hollow  part,  conventional,  p.  87,  §  59. 
Horizontal  plane  of  projection,  p.  73,  §  53. 


I. 

/,  description  of  the  letter,  p.  45,  §  38;  p.  65,  §  47. 
Inches,  symbol  for,  p.  95,  §  62. 
Inclined  lines  of  lettering,  p.  69,  §  49. 
Ink,  bottle  holder,  p.  112,  §  75. 
colored,  p.  18,  §  18. 
drawing,  p.  3,  §  2;  p.  18,  §  18;  p.  no,  §  75. 

requirements  of,  p.  18,  §  18. 

quantity  to  carry  on  pen,  p.  in,  §  75;  p.  137,  §  96. 
too  little  on  pen,  p.  in,  §  75. 
too  much  on  pen,  p.  ni,  §  75. 
Inked  lines,  blotting,  p.  in,  §  75. 
free-hand,  p.  136,  §  96. 
which  meet  or  intersect,  p.  in,  §  75. 
Inking  a  drawing,  p.  21,  §  21;  p.  no,  §  75. 

order  of,  p.  113,  §  75. 
Instrument  cleaner,  p.  4,  §  2;  p.  33,  §  30. 
Inside  calipers,  p.  32,  §  39. 
Inking  exercises,  in  free-hand  drawing,  p.  154,  §§  112-114. 

free-hand  lettering,  p.  56,  §  43;  p.  60,  §  46;  p.  67,  §  48. 
isometric  free-hand  drawing,  p.  171,  §  135  and  §  137. 
mechanical  drawing,  p.  110,  §  75. 
Instruments,  care  of,  p.  i,  §  i. 
drawing,  p.  3,  §  2. 
list  of,  p.  2,  §  2. 
quality  of,  p.  i,  §  i. 
rag  for  cleaning,  p.  4,  §  2;  p.  33,  §  30. 
selection  of,  p.  i. 

Intersecting  inked  lines,  p.  in,  §  75. 
Invisible  line,  p.  76,  §  54. 

threads,  p.  89,  §  59. 
Irregular  curves,  p.  2,  §  2;  p.  13,  §  12. 

selection  of,  p.  13,  §  12. 
use  of,  p.  13,  §  12. 
Isometrics,  p.  156,  §  116. 
Isometric  axes,  p.  158,  §  119. 

reversed,  p.  102,  §  124. 
conventional  thread,  p.  163,  §  126. 
drawing  of  a  lathe  cap,  p.  166,  §  130. 

plane  figure,  p.  160,  §  122. 
sphere,  p.  165,  §  129. 
wall,  p.  162,  §  124. 

Isometric  drawing,  offset  construction  in,  p.  164,  §  128. 
advantages  of,  p.  156,  §  116. 
and  sketching,  p.  156,  Chapter  V. 
definitions,  p.  158,  §  119. 


INDEX  185 

Isometric  drawing,  disadvantages  of,  p.  157,  §  116. 
of  a  circle,  p.  159,  §  120. 

approximate  method,  p.  160,  §  121. 
cube,  p.  157,  §  118. 
cube  cut  by  a  plane,  p.  161,  §  123. 
exercises,  set  of,  p.  167,  §  132  (see  also  Chapter  Viable  of 

Contents). 

principles  of,  p.  157,  §  117. 
line,  p.  158,  §  119. 
measurements,  p.  159,  §  119. 
of  a  cylinder,  p.  163,  §  125. 
of  a  half  sphere,  p.  165,  §  129. 

of  a  hollow  cylinder  with  section  removed,  p.  164,  §  127. 
of  one-eighth  sphere,  p.  166,  §  129. 
of  screw  threads,  p.  163,  §  126. 
origin,  p.  158,  §  119. 
position,  p.  159,  §  1 20. 
projection  plane,  p.  157,  §  117. 
sketching,  examination  in,  p.  174,  §  138. 
sketching  sheets,  p.  166,  §  131. 
Isometrics,  exercises  in,  p.  167,  §  132,  etc. 
principles  of,  p.  157,  §  117. 

J. 

J,  description  of  the  letter,  p.  53,  §  41;  p.  66,  §  47. 

K. 

.K,  description  of  the  letter,   p.  47,  §  38;  p.  65,  §  47. 
Key  or  chart  for  spacing,  p.  43,  §  35. 

L. 

L,  description  of  the  letter,  p.  45,  §  38;  p.  65,  §  47. 
Lathe,  speed,  perspective  drawing  of,  Frontispiece. 
Laying  out  or  blocking  out  a  drawing,  p.  84,  §  56. 
Lead  pencil,  p.  3,  §  2;  p.  14,  §  14. 
care  of,  p.  15,  §  14. 
selection  of,  p.  14,  §  14. 
to  sharpen,  p.  15,  §  14. 
Leader,  definition  of,  p.  97,  §  62. 
Lengthening  or  extension  bar,  p.  23,  §  22. 
Letter,  ability  to,  p.  34,  §  31. 
Lettering,  p.  34,  §  31.     Chapter  II. 

and  size  of  letter  sheets,  p.  44,  §  37. 

critical  study  of,  p.  36,  §  32. 

exercises  in,  p.  44,  §  38  (see  also  Chapter  II,  Table  of  Contents). 

in  bill  of  material,  p.  102,  §  67. 

inclined  lines  of  p.  69,  §  49. 

in  title  form,  p.  100,  §  66. 

on  working  drawings,  p.  34,  §  31. 

pens,  requirements  of,  p.  19,  §  19. 
to  break  in,  p.  20,  §  19. 

systematic  method  of,  p.  44,  §  36. 
Letter  A,  capital,  descr  ption  of,     p.  47,  §  38. 

Mnii  y  '.'      £  _     s    .  ^_ 


a,  small, 

B,  capital, 

b,  small, 

C,  capital, 

c,  small, 

D,  capital, 

d,  small, 


P-  63,  §  47- 
P-  53, 
p.  64, 

P-  52, 
p.  64, 

P-  52, 

P-  63,  §  47. 


i86 


INDEX 


Letter  E,  capital,  description  of,    p.  45,  § 

38. 

e,  small, 

'     P-  64,  § 

F,  capital, 

P-45,§ 

38^ 

f,  small, 

'            "     P-  66,  § 

47- 

G,  capital, 

"     P-  52,  § 

41. 

g,  small, 
H,  capital, 

"     P-64,§ 
p.  45,  § 

47- 
38. 

h,  small, 

'     p.  65,  § 

47- 

I,  capital, 

P-  45,  § 

38. 

i,  small, 

p.  65,  § 

47- 

J,  capital, 

"     P-  53,  § 

41. 

j,  small, 

"     P.66,§ 

47- 

K,  capital, 

p.  47,  § 

38. 

k,  small, 

p.  65,  § 

47- 

L,  capital, 

p.  45,  § 

38. 

1,  small, 

p.  65,  § 

47- 

M,  capital, 

"     P-46,§ 

38. 

m,  small, 

"     P-65,§ 

47- 

N,  capital, 

'           "p.  46,  § 

38. 

n,  small,                                p.  64,  § 

47- 

O,  capital,                             p.  51,  § 

41. 

o,  small,                           "     p.  63,  § 

47. 

P,  capital,                               p.  53,  § 

41. 

p,  small, 

p.  64,  § 

47- 

Q,  capital, 

p.  52,  § 

41. 

q,  small, 
R,  capital, 

P-  64,  § 
P-  53,  § 

47- 

r,  small, 

P-  65,  § 

47- 

S,  capital, 

p.  53,  § 

41. 

s,,  small, 

'            "     p.  66,  § 

47- 

T,  capital, 

P-  45,  § 

38. 

t,  small, 

1     P-  66,  § 

47- 

U,  capital, 

P-  52,  § 

41. 

u,  small, 

P-  65,  § 

47- 

V,  capital, 

"     P-4M 

38. 

v,  small, 

"     P-67,§ 

47- 

W,  capital, 

P-  47,  § 

38. 

w,  small, 

'     P-  67,  § 

47- 

X,  capital, 

P-  46,  § 

38. 

x,  small, 

p.  67,  § 

47- 

Y,  capital, 

"     P-46,§ 

38. 

y,  small, 

P-  65,  § 

47- 

Z,  capital, 

P-  47,  § 

38. 

z,  small, 

"     P-  67,  § 

47- 

&,  the  symbol,    '                  p.  54,  § 
Letters,  capital  or  upper-case  (see  Letters, 

General  Description  of). 

center  lines  for,  p.  37,  §  34. 
description  of  model,  p.  37,  §  34. 
distance  between,  p.  39,  §  35. 
general  appearance  of,  p.  35,  § 
lodel, 


32 


general  description  of  m 

§44;  p.  60,  §47. 
grouping  of,  p.  35,  §  32. 
guide  lines  for,  p.  37,  §  34- 
pattern,  p.  105,  §  70. 
slope  of,  p.  36,  §  33. 

in  this  work,  p.  37,  §  33. 
small,  p.  42,  §  35. 

small  or  lower-case  (see  Letter,  Description  of), 
spacing  key  or  chart  for,  p.  43,  §  35. 
spacing  of,  p.  39,  §  35. 

capital,  p.  40,  §  35- 
stem  of,  denned,  p.  37,  §  34. 


P.  37,  §345  P-  44,  §  38;  P-  5i,  §  4i;  P-  58,, 


INDEX  187 

Lettering,  examination  in,  p.  69,  §  51. 

inclined,  lines  of,  p.  69,  §  49. 
in  title  form,  p.  100,  §  66. 
study  of,  p.  34,  §  32. 
system  of  strokes  in,  p.  38,  §  34. 
Limits,  dimension,  p.  95,  §  62. 
Line,  an  isometric,  p.  158,  §  119. 

a  non-isometric,  p.  158,  §  119. 

a  "clear-cut,"  or  finished,  p.  78,  §  54. 

to  draw  an  inked,  p.  in,  §  75;  p.  136,  §  96. 

to  draw  a  pencil,  p.  134,  §  95. 
Liner,  section,  p.  82,  §  55. 
Lines,  border,  p.  106,  §  72. 

center,  p.  78,  §  54. 

construction  of,  p.  76,  §  54. 

conventional,  p.  76,  §  54;  p.  89,  §  59. 

dimension,  p.  77,  §  54. 

faulty,  p.  in,  §  75. 

finished,  p.  78,  §  54. 

free-hand  inked,  p.  136,  §  96. 

free-hand  penciled,  p.  135,  §  95. 

intersecting  inked,  p.  in,  §  75. 

invisible,  p.  76,  §  54. 

on  tracing  cloth,  p.  115,  §  77. 

reference,  p.  77,  §  54- 

section,  p.  77,  §  54. 

to  draw  free-hand,  p.  134,  §  95. 

to  draw  finished,  p.  78,  §  54. 

to  draw  parallel,  p.  13,  §  n. 

to  draw  perpendicular,  p.  12,  §  n. 

visible,  p.  76,  §  54. 

"weight"  of,  p.  76,  §  54. 
List  of  instruments  and  supplies,  p.  2,  §  2. 
Longitudinal  section,  p.  79,  §  55. 
Lower-case  or  small  letters  (see  also  Letters,  Description  of),  p.  60,  §  47. 


M. 

M,  description  of  the  letter,  p.  46,  §  38;  p.  65,  §  47. 
Machine  screws,  p.  126,  §  84. 
Machinist's  calipers,  p.  4,  §  2;  p.  32,  §  29. 
dividers,  p.  4,  §  2;  p.  33,  §  29. 
selection  of,  p.  32,  §  29. 
use  of,  pp.  32  and  33,  §  29. 
scale,  p.  4,  §  2;  p.  32,  §  29. 
Manila  covers,  p.  4,  §  2. 
Materials,  conventions  for,  p.  81,  §  55. 

abbreviations  for,  p.  103,  §  67. 
bill  of,  p.  101,  §  67. 
indicated  by  numbers,  p.  81,  §  55. 
Measurements,  p.  30,  §  27. 

in  isometric  drawing,  p.  159,  §  119. 
Mechanical  drawing,  Chapter  III,  p.  71,  §  52. 

examination  in,  p.  130,  §  90. 

principles  underlying,  p.  71,  §  52. 

set  of  exercises  in,  p.  116,  §  79  (see  also  Chapter  III,  Table 

of  Contents). 

Memory,  sketching  from,  p.  134,  §  94. 

Method  of  drawing  angles  with  triangles  and  T-square,  p.  12,  §  n. 
parallel  lines,  p.  13,  §  n. 


1 88  INDEX 

Micrometer,  p.  33,  §  29. 

Model  Letters,  general  description  of,  p.  37,  §  34. 

N. 

TV,  description  of  the  letter,  p.  46,  §  38;  p.  64,  §  47. 

National  acme  thread,  p.  89,  §  59. 

Naught,  the  numeral,  description  of,  p.  58,  §  44. 

Needle  point  for  instruments,  p.  24,  §  22. 

Nine,  description  of  the  numeral,  p.  58,  §  44. 

Non-isometric  lines,  p.  158,  §  119. 

Notes  on  a  drawing,  p.  73,  §  52;  p.  97,  §  63. 

style  of  lettering  for,  p.  98,  §  63. 
Number  and  arrangement  of  views,  p.  83,  §  56. 

reference  or  part,  p.  90,  §  59;  p.  104,  §  69. 

used  to  indicate  materials,  p.  81,  §  55. 
Numbering  and  size  of  sheets,  p.  139,  §  99;  p.  166,  §  131. 

of  drawings,  p.  103,  §  68. 

Numbers  (see  Numerals,  description  of),  p.  37,  §  34. 
Numeral  i,  description  of,  same  as  capital  I,  p.  45,  §  38. 


P-  59,  8  44- 
p.  59,  §  44. 
p.  58,  §  44. 
P-  59,  §  44- 


P-  59,  §  44- 
I!       P-S8,§44. 
P-  59,  §  44- 
"       P-  58,  §  44- 
naught,  description  of,  p.  58,  §  44. 
Numerals,  exercise  in  making,  p.  60,  §  45. 
spacing  of,  p.  42,  §  35. 

O. 

O,  description  of  the  letter,  p.  51,  §  41;  p.  63,  §  47. 
Objects,  sketches  of,  p.  132,  §  93. 
Offset  construction  in  isometric  drawing,  p.  164,  §  128. 
Operation  sheets,  p.  85,  §  57. 
Order  of  inking  a  drawing,  p.  113,  §  75. 
checking  a  drawing,  p.  113,  §  76. 
penciling  a  drawing,  p.  109,  §  74. 
Ordinary  pens,  p.  3,  §  2;  p.  18,  §  19. 

care  of,  p.  19,  §  19. 

selection  of,  p.  19,  §  19. 

use  of,  p.  137,  §  95. 
Origin,  isometric,  p.  158,  §  119. 
Orthographic  projection,  p.  73,  §  53- 
Outside  calipers,  p.  32,  §  29. 
Overall  dimensions,  p.  96,  §  62. 

P. 

P,  description  of  the  letter,  p.  53,  §  41;  p.  64,  §  47. 
Paper,  blue  print,  p.  2,  §  2;  p.  6,  §  7;  p.  116,  §  78. 

cross  section  ruled,  p.  2,  §  2;  p.  5,  §  4. 

drawing,  p.  2,  §  2;  p.  4,  §  3. 

fasteners,  p.  4,  §  2. 

isometric  ruled,  p.  2,  §  2;  p.  5,  §  4. 

ruled,  p.  2,  §  2;  p.  5,  §  4. 

to  fasten  on  drawing  board,  p.  107,  §  73. 

tracing,  p.  6,  §  5. 

Whatman's,  p.  5,  §  3. 


INDEX  189 


Parallel  lines,  method  of  drawing,  p.  13,  §  n. 
Part  or  reference  number,  p.  90,  §  59;  p.  104,  §  69. 
Part  numbers  in  bill  of  materials,  p.  102,  §  67. 
Parts,  detailed  on  a  single  sheet,  p.  85,  §  57. 

grouping  of,  on  a  single  sheet,  p.  85,  §  57. 
standard,  p.  103  §67;   p.  26,  §84. 
Pattern  letters  on  a  drawing,  p.  105,  §  70. 
Pattern  maker's  rule,  p.  92,  §  60. 
Pattern  numbers,  p.  105,  §  70. 

in  a  bill  of  material,  p.  102,  §  67. 
Patterns,  recording  on  a  drawing,  p.  104,  §  70. 
Pen,  quantity  of  ink  to  carry  on  a,  p.  137,  §  96. 
Pencil,  bow,  p.  3,  §  2;  p.  27,  §  25. 

drawing,  method  of  making  a,  p.  108,  §  74. 

eraser,  p.  3,  §  2;   p.  16,  §  15. 

lead,  p.  3,  §  2;  p.  14,  §  14. 

lines,  free-hand,  p.  134,  §  95. 

pointer  or  sharpener,  p.  3,  §  2;  p.  14,  §  13. 

sharpener  or  pointer,  p.  14,  §  13. 

sketching,  p.  134,  §  95. 

to  form  a  chiseled  edge  on  a,  p.  16,  §  14. 

cone  point  on  a,  p.  15,  §  14. 
to  sharpen  a,  p.  15,  §  14. 
Penciling,  order  in  which  to  do,  p.  109,  §  74. 
Penholders,  p.  3,  §  2;  p.  20,  §  20. 
Pens,  ball -pointed,  p.  3,  §  2;  p.  19,  §  19. 
bow,  p.  3,  §  2;  p.  28,  §  26. 
crow-quill,  p.  3,  §  2;  p.  19,  §  19. 
for  lettering,  p.  19,  §  19. 
ordinary,  p.  3,  §  2;  p.  18,  §  19. 
ruling  or  drawing,  p.  3,  §  2;  p.  20,  §  21. 
styles  of,  p.  18,  §  19. 
to  adjust  the  ruling,  p.  20,  §  21. 
to  clean  the  ruling,  p.  22,  §  21. 
to  fill  the  ruling,  p.  21,  §  21. 
to  sharpen  the  ruling,  p.  22,  §  21. 
to  test, -the  ruling,  p.  23,  §  21. 
use  of  the  ruling,  p.  21,  §  21. 
wiper  for,  p.  33,  §  3°- 
Pen-wiper,  p.  4,  §  2;  p.  33,  §  30. 
Perspective  drawing,  p.  71,  §  52. 
Plan  view,  p.  75,  §  53. 

Plane  figure,  isometric  drawing  of  a,  p.  160,  §  122. 
Planes  of  projection,  p.  73,  §  53. 
Position,  isometric,  p.  159,  §  120. 
Principles  of  mechanical  drawing,  p.  71,  §  52. 
isometric  drawing,  p.  157,  §  117. 
Problems  (see  Exercises) . 
Projecting  rays,  p.  73,  §  53. 
Projection,  p.  73,  §  53. 

isometric,  p.  157,  §  117. 
orthographic,  p.  73,  §  53. 
planes  of,  p.  73,  §  53. 
third  angle,  p.  74,  §  53;  p.  84,  §  56. 
Proportioning  by  eye,  p.  133,  §  93. 
Protractors,  p.  4,  §  2;  p.  31,  §  28. 
use  of,  p.  31,  §  28. 

Q. 

Q,  description  of  the  letter,  p.  52,  §  41;  p.  64,  §  47. 
Quarter -section  view,  p.  83,  §  55. 


I QO  INDEX 


R. 

R,  description  of  the  letter,  p.  53,  §  41;  p.  65,  §  47. 
Radius,  dimensioning  a,  p.  97,  §  62. 

symbol  or  abbreviations  for,  p.  97,  §  62. 
Rag,  instrument,  p.  4,  §  2;  p.  33,  §  30. 
Rays,  projection,  p.  73,  §  53. 
Record  forms  and  titles,  p.  98,  §  65. 

kept  on  a  drawing,  p.  98,  §  65. 
Recording  patterns  on  a  drawing,  p.  104,  §  70. 
Reference  lines,  p.  77,  §  54. 

or  part  numbers,  p.  90,  §  59;  p.  104,  §  69. 
Reversed  axes,  isometric,  p.  162,  §  124. 
Rhombus  (or  rhomb),  footnote,  p.  158. 
^Ruled  paper,  p.  2,  §  2;  p.  5,  §  4- 

care  and  use  of,  p.  5,  §  4. 

Rule  or  scale,  p.  3,  §  2;  p.  29,  §  27;  p.  32,  §  29. 
shrink,  p.  92,  §  60. 
special,  p.  92,  §  60. 
Rules  for  dimensioning,  p.  94,  §  62. 
Ruling  or  drawing  pens;  p.  3,  §  2;  p.  20,  §  21. 
care  of,  p.  22,  §  21. 
design  of,  p.  20,  §  21. 
to  adjust,  p.  20,  §  21. 
to  clean,  p.  22,  §  21. 
to  fill,  p.  21,  §  21. 
to  sharpen,  p.  22,  §  21. 
to  test,  p.  23,  §21. 
use  of,  p.  21,  §  21. 

S. 

S,  description  of  the  letter,  p.  53,  §  41;  p.  66,  §  47. 
Scale  or  rule,  p.  3,  §  2;  p.  29,  §  27;  p.  32,  §  29. 
architects',  p.  29,  §  27. 
care  of,  p.  31,  §  27. 
choice  of,  in  drawing,  p.  93,  §  61. 
design  of,  p.  29,  §  27. 
determining  the,  p.  93,  §  61. 
divisions  on  a,  p.  90,  §  60. 
drawing,  p.  90,  §  60. 
engineers',  p.  29,  §  27. 
flat,  p.  29,  §  27. 

for  several  parts  on  a  single  sheet,  p.  94,  §  61. 
machinists',  p.  4,  §  2;  p.  32,  §  29. 
most  commonly  used,  p.  91,  §  60. 
of  a  drawing,  p.  93,  §  61. 
to  draw  to,  p.  90,  §  60. 
to  read  a,  p.  91,  §  60. 
to  test  the  accuracy  of,  p.  31,  §  27. 
triangular,  p.  30,  §  27. 
use  of,  p.  30,  §  27. 
Screw  thread,  p.  72,  §  52;  p.  89,  §  59. 

conventionally  shown,  p.  89,  §  59. 
isometric  drawing  of,  p.  163,  §  126. 
Screws,  cap,  p.  128,  §  84. 

A.S.M.E.  standard,  p.  126,  §  84. 
machine,  p.  126,  §  84. 
various  forms  of,  p.  126,  §  84. 
Section,  a  turned-up,  p.  83,  §  55. 
compound,  p.  79,  §  55. 
liner,  p.  82,  §  55. 


INDEX  IQI 

Section,  lines,  p.  77,  §  54- 

longitudinal,  p.  79,  §  55. 
transverse,  p.  79,  §  55. 
Sectional  views,  p.  79,  §  55. 

location  of,  p.  83,  §  55. 
Sectioning  adjoining  pieces,  p.  82,  §  55. 
an  area,  p.  82,  §  55. 
and  sectional  views,  p.  79,  §  55. 
conventional,  p.  79,  §  55. 
isometric,  p.  164,  §  127. 
ordinary,  p.  81,  §  55. 
spacing  of  lines  in,  p.  82,  §  55. 
Selection  of  instruments,  p.  i,  §  i. 
Sentences,  spacing  between,  p.  42,  §  35. 
Set  of  free-hand  drawing  exercises,  p.  139,  §  100,  etc. 

isometric  drawing  exercises,  p.  167,  §  132,  etc. 
lettering  exercises,  p.  44,  §  38,  etc. 
mechanical  drawing  exercises,  p.  116,  §  79,  etc. 
Seven,  description  of  the  numeral,  p.  58,  §  44. 
Shaft,  conventionally  shown,  p.  87,  §  59. 
Sharpener,  pencil,  p.  3,  §  2;  p.  14,  §  13. 
Sheets,  operation,  p.  85,  §  57. 

size  and  numbering  of,  p.  139,  §  99;  p.  166,  §  131. 
title  form  for,  p.  138,  §  98. 
Shield,  erasing,  p.  3,  §  2;  p.  17,  §  16. 
Shrink  rule,  p.  92,  §  60. 
Side  elevations,  p.  75,  §  53. 

Size  and  numbering  of  sheets,  p.  139,  §  99;  p.  166,  §  131. 
Six,  description  of  the  numeral,  p.  59,  §  44. 

and  lettering  of  letter  sheets,  p.  44,  §  37. 
and  numbering  of  drawings,  p.  103,  §  68. 
Sketches,  free-hand,  from  objects,  p.  132,  §  93. 
on  cross-section  paper,  p.  133,  § 
value  and  use  of,  p.  131,  §  91. 
Sketching,  examination  in  free-hand  exercises  (see  Exercises  in  Free-hand  Drawing 

and  Exercises  in  Isometric  Free-hand  Sketches),  p.  154,  §115. 
Sketching  from  memory,  p.  134,  §  94. 
Sketch  sheets,  size  and  numbering  of,  p.  139,  §  99;  p.  166,  §  131. 

to  build  up  a,  p.  137,  §  97. 
Slope  of  fractions,  p.  60,  §  45. 

letters,  p.  36,  §  33. 
Sloping  ellipse,  p.  50,  §  40. 
Small  or  lower-case  letters,  detail  description  of  (see  also  Letters),  p.  60,  §  47. 

spacing  of,  p.  42,  §  35. 
Soapstone,  p.  3,  §  2;  p.  18,  §  17. 

use  of,  p.  18,  §  17. 

Soda,  carbonate  of,  p.  4,  §  2;  p.  116"  §  78. 
Spacing  for  various  line-combinations  in  lettering,  p.  39,  §  35. 
Speed  lathe,  perspective  of,  Frontispiece. 
Sphere,  isometric  drawing  of  a,  p.  165,  §  129. 
Spacing,  key  or  chart  for,  p.  43,  §  35. 

between  section  lines,  p.  82,  §  55. 
of  capital  letters,  p.  40,  §  35. 
of  numerals,  p.  42,  §  35. 
of  words  and  sentences,  p.  42,  §  35. 
Standard  parts,  p.  103,  §  67;  p.  126,  §  84. 
Steel  scale,  p.  4,  §  2;  p.  32,  §  29. 
Structural  steel  cross-sections,  p  90,  §  59. 
Studs,  p.  127,  §  84. 
Square,  T-,  p.  2,  §  2;  p.  8,  §  10. 
Square  thread  conventionally  shown,  p.  89,  §  59. 


IQ2  INDEX 

Steel  shapes,  conventional,  p.  90,  §  59. 

Stem  of  letters,  p.  37,  §  34. 

Strokes,  system  of,  in  lettering,  p.  38,  §  34. 

Study  of  lettering,  p.  34,  §  32. 

Sub-dimensions,  p.  96,  §  62. 

Supplies,  list  of,  p.  2,  §  2. 

quality  of,  p.  i,  §  i. 
Surfaces,  finished,  p.  98,  §  64. 
Symbols  on  a  drawing,  p.  72,  §  52. 
Symbol  for  "center  line,"  p.  78,  §  54. 

"inches,"  p.  95,  §  62. 

Systematic  method  of  lettering,  p.  44,  §  36. 
System,  drawing-room,  p.  175,  Appendix  A. 

T. 

r,  description  of  the  letter,  p.  45,  §  38;  p.  66,  §  47. 
T-square,  p.  2,  §  2;  p.  8,  §  10. 
care  of,  p.  10,  §  10. 
design  of,  p.  9,  §  10. 
test  of,  p.  9,  §  10. 
use  of,  p.  10,  §  10. 

Table  of  U.  S.  standard  bolts,  p.  127,  §  84. 
Tacks,  thumb,  p.  2,  §  2;  p.  8,  §  9. 
Tail  stock,  assembly  of,  Frontispiece. 
Tapers,  dimensioning,  p.  97,  §  62. 
Tapped  holes,  conventionally  shown,  p.  90,  §  59. 

dimensioning,  p.  97,  §  62. 
Test  for  T-square,  p.  9,  §  10. 

ruling  pen,  p.  23,  §  21. 
triangles,  p.  u,  §  12. 

Third  angle  projection,  p.  74,  §  53;  p.  84,  §  56. 
Threads,  conventionally  shown,  p.  72,  §  52. 
Thread,  invisible,  p.  89,  §  59. 

National  Acme,  p.  89,  §  59. 
square,  conventional  p.  89,  §  59. 
V,  conventional,  p.  89,  §  59. 
Threaded  piece,  dimensioning  a,  p.  97,  §  62. 

portion,  length  of,  p.  89,  §  59. 
Three,  description  of  the  numeral,  p.  59,  §  44. 
Threads,  forms  of,  p.  89,  §  59. 
Thumb  tacks,  p.  2  §  2;  p.  8,  §  9. 

selection  of,  p.  8,  §  9. 
.       use  of,  p.  8,  §9. 
Time-keeping  in  drawing,  p.  105,  §  71. 
Timber,  conventionally  shown,  p.  87,  §  59. 
Title  form  on  a  drawing,  p.  100,  §  66. 

small  sheets,  p.  138,  §  98. 
Titles  and  headings,  design  of,  p.  69,  §  49. 

on  a  drawing,  p.  69,  §  49;  p.  98,  §  65. 
Tracing,  p.  114,  §  77. 

care  of,  p.  6,  §  6;  p.  115,  §  77. 
cloth,  p.  2,  §  2;  p.  6,  §  6. 

choice  of  working  side,  p.  6,  §  6;  p.  115,  §  77. 
to  clean,  p.  115,  §  77. 
to  fasten  on  drawing  board,  p.  107,  §  73. 
use  of,  p.  6,  §  6. 
erasures  on  a,  p.  115,  §  77. 
exercises  in  (see  also  set  of  Mechanical  Drawing  Exercises  in,  Table  of 

Contents,  Chapter  III), 
paper,  p.  6,  §  5. 
to  make  a,  p.  114,  §  77. 


INDEX  193 


Transverse  section,  p.  79,  §  55. 
Triangle,  p.  2,  §  2;  p.  10,  §  n. 

selection  of,  p.  10,  §  n. 

use  of,  p.  12,  §  ii. 

test  for  90°  angle  of  a,  p.  II,  $  XI. 
45°  angle  of  a,  p.  11,  §  11. 
30   also  60   angle  of  a,  p.  12,  §  11. 
Triangular  scales,  p.  30,  §  27. 
Turned-up  section,  p.  83,  §  55. 
Two,  description  of  the  numeral,  p.  59,  §  44. 

U. 

U,  description  of  the  letter,  p.  52,  §  41;  p.  65,  §  47. 
Upper-case  or  capital  letters  (see  Letters,  Description  of). 
U.  S.  standard  bolts,  p.  127,  §  84. 

V. 

V,  description  of  the  letter,  p.  46,  §  38;  p.  67,  §47. 

Vertical  plane  of  projection,  p.  73,  §  53. 

View,  plan,  front  and  side,  p.  75,  §  53. 

Views,  arrangement  of,  p.  75,  §  53;  p.  83,  §  56. 

how  to  work  up,  p.  74,  §  53;  p.  86,  §  57;  p.  109,  §  74. 

number  of,  p.  83,  §  56;  p.  103. 

projected,  p.  73,  §  53. 
Visible  lines,  p.  76,  §  54. 
V  thread,  conventional,  p.  89,  §  59. 

W. 

W,  description  of  the  letter,  p.  47,  §  38;  p.  67,  §  47. 
Wall,  isometric  drawing  of  a,  p.  162,  §  124. 
Wedge,  pencil  sharpened  to  a,  p.  16,  §  14. 
Weight  of  lines,  p.  76,  §  54. 
Whatman  paper,  p.  5,  §  3. 
Wiper,  pen,  p.  4,  §  2;  p.  33,  §  30. 
Words,  spacing  between,  p.  42,  §  35. 
Working  drawings,  dimensioning,  p.  94,  §  62. 

X. 

X,  description  of  the  letter,  p.  47,  §  38;  p.  67,  §  47. 

Y. 

F,  description  of  the  letter,  p.  46,  §  38;  p.  65,  §  47. 

Z. 

Z,  description  of  the  letter,  p.  47,  §  38;  p.  67,  §  47. 


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